Biomaterial compositions

ABSTRACT

Biomaterial compositions comprising organosilicon monomers (such as silorane monomers) and chemical curing systems or dual chemical/light curing systems, in conjunction with optional tetraoxaspiro[5.5]undecanes (“TOSUs”) and/or fillers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a Divisional of U.S. patentapplication Ser. No. 13/880,783, filed on Apr. 22, 2013, which is 371application from PCT/US2011/058381, filed on Oct. 28, 2011, which isbased on and claims priority to U.S. Provisional Application Ser. No.61/456,045, filed on Oct. 29, 2010, each of which is incorporated hereinby reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Department ofDefense/USA Medical Research AQC Award No. W81XWH-07-1-0696. Thegovernment has certain rights in the invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to compositions of matter and moreparticularly, to compositions useful as biomaterials. The compositionscomprise organosilicon monomers (preferably silorane monomers) andchemical curing systems or dual chemical/light curing systems. Thecompositions may include one or more tetraoxaspiro[5.5]undecanes(“TOSUs”) and/or fillers. Photoacids, photosensitizers and/or a reactionpromoters (electron donors) may also be included in the composition. Thepolymerizable compositions of the present invention are useful for avariety of applications, including use as biomaterials, for example asbone cements, bone stabilizers, dental composites, crowns, and the like.

2. Description of Related Art

Bone fractures are suffered by nearly six million Americans each year.The common methods for fracture stabilization such as casts, splinting,intramedullary pinning, and external fixation, do have their drawbacksespecially with regards to stabilization of small and growing bones. Inaddition to hampering soft tissue management, splinting cannotadequately stabilize highly unstable fractures or injuries withconsiderable bone loss. There must be sufficient bone cortex to supportpin stabilization, especially with epiphyseal (near the end of the bone)fractures. These fractures lacking sufficient cortex often require pinplacement across the adjacent joint leading to joint stiffness.Fractures in children can be further complicated by rapid growth ofbone, thus requiring continual adjustment of the stabilizationtechnique.

Frequently, bone cement has been used to stabilize fractures. Thecurrent bone cements are methacrylate based systems packaged in twocomponents. The powder contains a mixture of polymethyl methacrylate(“PMMA”), methyl methacrylate-styrene-copolymer, and a radio opacifier(either barium sulfate or zirconium oxide). The second component is aliquid monomer typically containing methyl methacrylate,N,N-dimethyl-p-toluidine, and hydroquinone. The cure time ofcommercially available PMMA bone cements ranges from 6 to 22 minutes,and reaches a peak exotherm from 75 to 110° C. Thermal finite elementmodels have found temperatures in excess of 60° C. at the bone cementand cancellous bone interface. The fracture toughness of bone cementsgenerally ranges from 1.0 to 1.5 MPa/m². Flexural strength of bonecements ranges from 60 to 75 MPa and flexural modulus is between 2.2 and3.3 GPa. Bone cements typically have a tensile strength of 50 to 60 MPa.These property values all meet or surpass the requirements described inISO 5833 Implants for Surgery—Acrylic Resin Cements.

PMMA was first used in orthopedic surgery by Sir John Charnley for totalhip arthroplasty in 1970 and the current formulation is essentiallyunchanged. Bone cement has different properties than other PMMA resins,due to both its additives and how it is prepared. Although the fullypolymerized form of PMMA has good compatibility with human tissue, thereare several drawbacks to its use. The monomer component is antigenic andinduces severe toxicity, contraction with polymerization, and intenseheat generation. These cements are highly exothermic, and have beenshown to cause thermonecrosis in animal models. Bone cement typicallyhas voids due to volatilization of the monomer during polymerization,which results in a porosity of 3 to 11%. Pressurization of the resin, asoccurs during implantation of a femoral bone, can raise the boilingpoint of the monomer and decrease pore formation and size, but can beproblematic if air is carried into the resin during implantation. Thevolume contracts by 5-7% during polymerization. This causes internalpores which can serve as crack initiators. The heat generated isdetermined by thickness/weight of resin, with a peak temperature rise inthe range of 75-85° C. Although PMMA is biologically compatible, themonomer is an irritant and possible carcinogen. Unreacted residualmonomer, approximately 3% after one hour, is present in the hardenedpolymer and can affect strength while leaching out into tissues,potentially causing hypotension, a common problem which can lead topossible cardiopulmonary events. The bone-resin interface is achieved bymechanical interlock, because the PMMA has no inherent adhesiveproperties. Dense bone causes less resin penetration, which can be anissue for resin fixation in younger patients such as military recruitswhose bone structure may have less trabecular porosity. Use of bonecement in hip arthroplasties has also been shown to increase systematiclevels of gamma-glutamytransperptidase (“GGTP”), which can result inanorexia and nausea/vomiting. Other drawbacks to the use of PMMA-basedcements include lack of bioactivity, volumetric shrinkage uponpolymerization, toxicity of the activator (N,N-dimethyl-p-toluidine) andpossible involvement of the radiopacifier in third body wear. Therefore,it would be desirable to provide an alternative bone cement toPMMA-based cement.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to biomaterial compositions, as wellas methods for manufacturing the same, and methods of using thecompositions. The biomaterial composition comprises one or moreorganosilicon monomers (such as a silorane) and a chemical curing systemor dual chemical/light curing system for polymerizing the monomer(s).The compositions may include one or more tetraoxaspiro[5.5]undecanes(“TOSUs”) and/or fillers. Accelerators (such as photoacids),photosensitizers, and/or electron donors may also be included in thecomposition as appropriate.

The biomaterial compositions of the present invention are comparable toor superior to conventional PMMA systems in many characteristics. Forexample, in one aspect of the present invention, the compositions of thepresent invention exhibit significantly less polymerization stresswithout an associated proportional reduction in mechanical properties.In another aspect of the present invention, the biomaterial compositionsexhibit enhanced biocompatibility and reduced cytotoxicity andgenotoxicity. In general, the compositions of the present invention willnot generate the cytotoxicity, antigenicity, polymerization stress, andheat generation that are characteristic of conventional PMMA bonecements.

In another aspect, it is anticipated that the biomaterial compositionsof the present invention exhibit a peak exotherm below 50° C., morepreferably below 45° C. For example, the silorane-based compositions ofthe present invention may exhibit a peak exotherm below about 49, 48,47, 46, 45, 44, 43, 42, 40, 39, 38, 37, 36, 35, 33, 32, 31, or 30° C.Most preferably, the peak exotherm is within 1, 2, 3, 4, or 5° C. of thebody temperature of the patient. For example, the P1 system (chemicalcuring system) and P2 systems (dual chemical/light curing system)described herein typically exhibit a peak exotherm of about 25 to 30° C.As such, it is anticipated that the biomaterial compositions of thepresent invention will not cause thermal necrosis.

The low exotherm of the chemically or dual cured silorane biomaterial(about 25- to 30° C.) compared to commercially available bone cement(about 70 to 90° C.) is an important property of the compositions of thepresent invention. Many antimicrobial agents and growth factors exhibitheat sensitivity. For example, proteins are degraded or denatured withincreasing heat leading to inactivation or conversion to compounds withpotential toxicity. Even antimicrobial agents such as silver (thoughrelatively heat insensitive) may exhibit some heat sensitivity incertain crystalline forms. Importantly, conventional bone cements havenot included growth factors (such as bone morphogenetic protein 2) dueto their thermal instability. See Prountos et al., The effect ofantibiotics on bone healing: current evidence, Expert Opin Drug Saf. 10935-945 (2011); Yano et al., Osteoinductive capacity and heat stabilityof recombinant human bone morphogenetic protein-2 produced byEscherichia coli and dimerlized by biochemical processing, J Bone MinerMetab 17 355-363 (2009); and Landry et al., The kinetics of thermalinstability in nanocrystalline silver and the effect of heat treatmenton the antibacterial activity of nanocrystalline silver dressings,Biomaterials 30 6929-6939 (2009). With the lower exotherm of thesilorane biomaterial compositions of the present invention,antimicrobials and growth factors (such cartilage or bone growthfactors, e.g., cartilage-derived morphogenic proteins or bonemorphogenic proteins) should remain stable. In one aspect, thebiomaterial composition contains growth factors selected from the groupconsisting of TGFβ1, TGFβ2, TGFβ3, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6,BMP-7, BMP-8, BMP-9, CDMP-1, CDMP-2, or CDMP-3.

In another aspect, the biomaterial compositions of the present inventionexhibit flexural strength greater than about 20 MPa, and preferablygreater than about 50 MPa. For example, the flexural strength may begreater than about 20, 30, 40, 50, 55, 60, or 65 MPa (or have a value ofsome range therebetween), with higher flexural strengths beingpreferred. For example, the P1 system (chemical curing system) typicallyexhibits a flexural strength of about 22 to 33 MPa, and the P2 systems(dual chemical/light curing system) described herein typically exhibit aflexural strength of about 25 to 60 MPa.

In another aspect, biomaterial compositions of the present inventionexhibit a flexural modulus greater than 1.5 GPa. For example, theflexural modulus may be greater than about 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,2.1, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, or 4.0 GPa (or have avalue of some range therebetween). For example, the P1 system (chemicalcuring system) typically exhibits a flexural modulus of about 1.5 to 1.7GPa, and the P2 systems (dual chemical/light curing system) typicallyexhibit a flexural strength of about 2.2 to 3.5 GPa.

In another aspect, the biomaterial compositions of the present inventionhave a handling time between 5 and 15 minutes (e.g., 5, 6, 7, 8, 9, 10,11, 12, 13, 14, or 15 minutes (or some range therebetween), andpreferably no longer than 20 minutes, when measuring the period of timerequired for the compositions to harden or “set” according to theGillmore Needle Test (ASTM C266-89). For example, the P1 system(chemical curing system) and P2 systems (dual chemical/light curingsystem) described herein typically exhibit a handling time of about 8 to10 minutes.

Therefore, the present invention is directed to a biomaterialcomposition which is an alternative to PMAA based bone cements. Forexample, an ideal bone cement composition will (1) provide atime-efficient means of reducing even small bone fragments toanatomically correct positions; (2) have the same loading response asnatural bone; (3) be biocompatible; (4) possess the handling propertiesto allow for the surgeon/technician to successfully place the materialin the fracture site in a controlled manner; and/or (5) not to integratewith the bone, but be easily removed without significantly destroyingthe tissue. It is anticipated that the biomaterial compositions of thepresent invention will have one or more of these properties, andpreferably all of these properties.

The biomaterial compositions may be used as a bone and dental cement,bone filler, bone anchor, and bone graft in patients. For example,potential applications for the biomaterial composition include, but arenot limited to bone cement (the adhesive or material used to join bonefragments together or for placement and anchorage of prostheticdevices); replacement of cartilage found in joints, e.g., knee meniscus,temporomandibular joint, wrist, etc.; vertebroplasty (the augmentationor mechanical support of a compromised vertebrae); bone filler (thematerial that fills cavities in bone either permanently or temporarilyas new bone fills in the defect); bone scaffold; adjunct to metal cagesfor spinal fixation with screws (the biomaterial may provide additionalmechanical support); and support of fractures to non-weight bearingbones (e.g., the orbital bones of the face; and prosthetic spinal discnucleus.). The biomaterial compositions of the present invention mayalso be used for the delivery of heat sensitive agents—includingheat-sensitive antimicrobials and growth factors—due to its lowexotherm. For example, the biomaterial compositions—combined with aheat-sensitive antimicrobial or growth factor—may be in the form of aspacer, or as beads or in another vehicular form.

Additional aspects of the invention, together with the advantages andnovel features appurtenant thereto, will be set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the following, or may be learnedfrom the practice of the invention. The objects and advantages of theinvention may be realized and attained by means of the instrumentalitiesand combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows cell growth responses of MLO-A5 cells for chemically curedsilorane resins (DCA, DCB, DCC) compared to the light cured siloraneresin (PIH) after culturing resins with cells for 24 and 48 hours.Panels a-d are from Trypan blue data and panels e and f are from MTTdata. The asterisk (*) defines significantly different values (p<0.05)from the light cure silorane (PIH).

FIG. 2 shows that the in vitro biocompatibility of the chemical curesilorane resin (SilMix CC) is comparable to the light cure siloraneresin (SilMix LC) as demonstrated by the similar number of live and deadadherent and non-adherent cells counted after 24 and 48 hours incubationwith MLO-A5 cells.

FIG. 3 shows that the ultimate load to fracture of excised mouse femorais similar when stabilized with either photoinitiated or dualchemical/light cured silorane resin.

FIG. 4 shows the chemical and dual chemical/light cured silorane stressand modulus measurements. Panels a and b illustrate the flexuralstrength and flexural modulus of the P1 and P2 systems compared toconventional PMMA systems. Panels c and d illustrate the flexturalstrength and modulus of two exemplary P1 systems. Panel e illustratesthe stress-strain curve for an exemplary neat dual chemical/light curedsystem comprising acetic acid, PIH, and camphorquinone.

FIG. 5 shows the exotherm temperature data for photoinitiated andchemically initiated silorane resins. These results show that thephotoinitiated silorane has a much higher exotherm (127° C.) than thechemically initiated (40° C.). The chemically initiated silorane alsohas a longer curing time. Note that the curing time presented for thechemical cure does not take into account the additional one minute ofmixing.

FIG. 6 is photographs of the silorane bone cement mimics. The firstsample (BCM 1/2) did not mix well and formed a gritty clump of material.However, samples BCM 3/4 and BCM 5/6 were much smoother and polymerizedwith a glossy finish.

FIG. 7 is an exotherm profile of six exemplary biomaterial compositionsin accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

In the following description, certain details are set forth such asspecific quantities, sizes, etc. so as to provide a thoroughunderstanding of the present embodiments disclosed herein. However, itwill be obvious to those skilled in the art that the present disclosuremay be practiced without such specific details. In many cases, detailsconcerning such considerations and the like have been omitted inasmuchas such details are not necessary to obtain a complete understanding ofthe present disclosure and are within the skills of persons of ordinaryskill in the relevant art.

The terms “comprises,” “comprising,” and variations thereof do not havea limiting meaning where these terms appear in the description andclaims.

The recitation herein, of numerical ranges by endpoints is intended toinclude all numbers subsumed within that range (e.g., 1 to 5 includes 1,1.5, 2, 2.75, 3, 3.80, 4, and 5).

As used herein, “a” or “an” means “at least one” or “one or more” unlessotherwise indicated. In addition, the singular forms “a,” “an,” and“the” include plural referents unless the content clearly dictatesotherwise. Thus, for example, reference to a composition containing “acompound” includes a mixture of two or more compounds. As used in thisspecification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

Unless otherwise indicated, all numbers expressing quantities ofcompounds, measurement of properties, and claims are to be understood asbeing modified in all instances by the term “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in theforegoing specification and attached claims are approximations that canvary depending upon the desired properties sought to be obtained bythose skilled in the art utilizing the teachings of the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of the invention are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviations foundin their respective testing measurements.

As used herein, the term “patient” encompasses humans and domesticanimals including pets and farm animals, exotic animals as found in zoosand similar preserves, and research animals as used in public andprivate research institutions, e.g., monkeys, chips, cats, dogs, horses,pigs, sheep, cows, monkeys, rats, mice, guinea pigs, and rabbits.

As used herein, the term “chemical cure” refers to a catalytic systemcapable of catalyzing them polymerization of the organosilicon monomers(preferably silorane monomers) described herein independent of light.While the chemical cure system may optionally include one or morecomponents of a light initiation system (e.g., PIH), the chemical curesystem is capable of polymerizing the organosilicon monomers (preferablysilorane monomers) in the dark.

As used herein, the term “dual” curing system means and refers to asystem that cures at least partially by light-cure (electromagneticradiation) and at least partially by a chemical cure. As discussed morefully below, the dual chemical/light curing system may contain on ormore accelerators, photosensitizers, and/or reaction promoters. Light(typically ultraviolet, visible, or infrared) is needed in order for thecomplete curing to occur.

Molecular terms, when used in this application, have their commonmeaning unless otherwise specified. It should be noted that thealphabetical letters used in the formulas of the present inventionshould be interpreted as the functional groups, moieties, orsubstituents as defined herein. Unless otherwise defined, the symbolswill have their ordinary and customary meaning to those skilled in theart.

The term “alkyl” embraces a branched or unbranched saturated hydrocarbongroup of 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, tetradecyl, as wellas cyclic alkyl groups and the like.

The term “alkoxy” embraces an alkyl group attached to an oxygen.Examples include, without limitation, methoxy, ethoxy, tert-butoxy, andcyclohexyloxy. Most preferred are “lower alkoxy” groups having one tosix carbon atoms. Examples of such groups include methoxy, ethoxy,propoxy, butoxy, isopropoxy, and tert-butoxy groups.

The term “alkenyl” embraces unsaturated aliphatic groups analogous inlength and possible substitution to the alkyls described above, but thatcontain at least one double bond. Examples include propenyl, 1-butenyl,2-butenyl, 3-butenyl, 2-methylpropenyl, 1-pentenyl, 2-pentenyl,3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 2-methyl-1-butenyl,3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl,3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl,3-methyl-3-butenyl, and the like.

The term “alkenoxy” embraces an alkenyl group attached to an oxygen.Examples include allyloxy, 1-propenyloxy, isopropenyloxy, methallyloxy,2-butenyloxy, 1-butenyloxy, isobutyloxy, pentenyloxy, hexenyloxy,octenyloxy, or decenyloxy.

The term “alkenoxyalkyl” embraces an alkenoxy-substituted alkyl moiety.Examples include allyloxymethyl, allyloxyethyl, allyloxypropyl, andmethallyoxymethyl.

The term “aryl” embraces a carbocyclic aromatic system containing one,two, or three rings wherein such rings may be attached together in apendant manner or may be fused. The term “fused” means that a secondring is present (i.e., attached or formed) by having two adjacent atomsin common (i.e., shared) with the first ring. The term “fused” isequivalent to the term “condensed.” The term “aryl” embraces aromaticgroups such as phenyl, naphthyl, tetrahydronaphthyl, indane, andbiphenyl.

The term “arylalkyl” or “aralkyl” embrace aryl-substituted alkylmoieties. Preferable aralkyl groups are “lower aralkyl” groups havingaryl groups attached to alkyl groups having one to six carbon atoms.Examples of such groups include benzyl, diphenylmethyl, triphenylmethyl,phenylethyl, and diphenylethyl. The terms benzyl and phenylmethyl areinterchangeable.

The term “aryloxy” embraces aryl groups, as defined above, attached toan oxygen atom, such as phenoxy.

The term “aralkoxy” or “arylalkoxy” embrace aralkyl groups attachedthrough an oxygen atom to other groups. “Lower aralkoxy” groups arethose phenyl groups attached to lower alkoxy group as described herein.Examples of such groups include benzyloxy, 1-phenylethoxy,3-trifluoromethoxybenzyloxy, 4-propylbenzyloxy, and 2-phenylethoxy.

The term silyl refers to the group —SiH₃. The silyl group may beoptionally substituted with one or more alkyl, aryl, arylalkyl, alkoxy,aryloxy, arylalkoxy groups, or combinations thereof. Thus, for example,the term “alkylsilyl” embraces a silyl group substituted with one ormore alkyl groups, such as methylsilyl, dimethylsilyl, trimethylsilyl,ethylsilyl, diethysilyl, triethylsilyl, and the like. The term“arylsilyl” similarly refers to a silyl group substituted with one ormore aryl groups, such as phenylsilyl. The term “arylalkylsilyl” refersto a silyl group substituted with one or more arylalkyl groups. The termalkoxysilyl refers to a silyl group substituted with one or more alkoxygroups. The term “aryloxysilyl” embraces silyl groups substituted withone or more aryloxy groups. The term “arylalkoxysilyl” embraces silylgroups substituted with one or more arylalkoxy groups.

The term “siloxy” embraces oxy-containing groups substituted with asilyl group. The siloxy group may be optionally substituted with one ormore alkyl, aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy groups, orcombinations thereof. Thus, for example, the term “alkylsiloxy” embracesa siloxy group substituted with one or more alkyl groups. The term“arylsiloxy” embraces a siloxy group substituted with one or more arylgroups. The term “arylalkylsiloxy” embraces a siloxy group substitutedwith one or more arylalkyl groups. The term “alkoxysiloxy” embraces asiloxy group substituted with one or more alkoxy groups. The term“aryloxysiloxy” embraces a siloxy group substituted with one or morearyloxy groups. The term “arylalkoxysiloxy” embraces a siloxy groupsubstituted with one or more arylalkoxy groups.

The term “silylalkyl” embraces silyl-substituted alkyl moieties. Thesilylalkyl groups may be optionally substituted with one or more alkyl,aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy groups, or combinationsthereof. Thus, for example, the term “alkylsilylalkyl” embracesmethylsilylpropyl, dimethylsilylpropyl, trimethylsilylpropyl, and thelike. The term “arylsilylalkyl” embraces aryl-substituted silylalkylgroups. The term “arylalkylsilylalkyl” embraces arylalkyl substitutedsilylalkyl groups. The term “alkoxysilylalkyl” embraces alkoxysubstituted silylalkyl groups. The term “aryloxysilylalkyl” embracesaryloxy substituted silylalkyl groups. The term “arylalkoxysilylalkyl”embraces arylalkoxy substituted silylalkyl groups.

The term “siloxyalkyl” embraces siloxy-substituted alkyl groups. Thesiloxyalkyl groups may be optionally substituted with one or more alkyl,aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy groups, or combinationsthereof. Thus, the term “alkylsiloxyalkyl” embraces alkyl substitutedsiloxyalkyl groups. The term “arylsiloxyalkyl” embraces aryl substitutedsiloxyalkyl groups. The term “arylalkylsiloxyalkyl” embraces arylalkylsubstituted siloxyalkyl groups. The term “alkoxysiloxyalkyl” embracesalkoxy substituted siloxyalkyl groups. The term “aryloxysiloxyalkyl”embraces aryloxy substituted siloxyalkyl groups. The term“arylalkoxysiloxyalkyl” embraces arylalkoxy substituted siloxyalkylgroups.

The term “silylalkoxy” embraces silyl-substituted alkoxy groups. Thesilylalkoxy group may be optionally substituted with one or more alkyl,aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy groups, or combinationsthereof. Thus, for example, the term “alkylsilylalkoxy” embraces alkylsubstituted silylalkoxy groups. The term “arylsilylalkoxy” embraces arylsubstituted silylalkoxy groups. The term “arylalkylsilylalkoxy” embracesarylalkyl substituted silylalkoxy groups. The term “alkoxysilylalkoxy”embraces alkoxy substituted silylalkoxy groups. The term“aryloxysilylalkoxy” embraces aryloxy substituted silylalkoxy groups.The term “arylalkyloxysilylalkoxy” embraces arylalkyloxy substitutedsilylalkoxy groups.

The term “siloxyalkoxy” embraces siloxy-substituted alkoxy groups. Thesiloxyalkoxy group may be optionally substituted with one or more alkyl,aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy groups, or combinationsthereof. Thus, for example, the term “alkylsiloxyalkoxy” embraces alkylsubstituted siloxyalkoxy groups. The term “arylsiloxyalkoxy” embracesaryl substituted siloxyalkoxy groups. The term “arylalkylsiloxyalkoxy”embraces arylalkyl substituted siloxyalkoxy groups. The term“alkoxysiloxyalkoxy” embraces alkoxy substituted siloxyalkoxy groups.The term “aryloxysiloxyalkoxy” embraces aryloxy substituted siloxyalkoxygroups. The term “arylalkoxysiloxyalkoxy” embraces arylalkyloxysubstituted siloxyalkoxy groups.

The biomaterial composition of the present invention comprises anorganosilicon monomer (such as a silorane) and a chemical curing systemor dual chemical/light curing system for polymerizing the monomer. Thecompositions may also contain TOSUs and/or fillers. The compositions mayalso include one or more accelerators, such as photoacids.Photosensitizers, and/or reaction promoters may also included in thebiomaterial composition having the dual chemical/light curing systems.In addition, one or more pre-polymerized organosilicon monomers may alsobe included in the biomaterial composition. The pre-polymerizedorganosilicon monomers essentially function as a filler in the overallbiomaterial composition.

In an exemplary aspect, the biomaterial composition comprises about 30to 60 wt % (e.g., about 30, 35, 40, 45, 50, 55, or 60 wt %—mostpreferably about 40 to 55 wt %) organosilicon monomer (e.g., siloraneco-monomer, such as SilMix); about 0 to 50 wt % (e.g., about 1, 2, 3, 4,5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 wt %—most preferably about 25to 50 wt %) pre-polymerized organosilicon monomer (e.g., pre-polymerizedsilorane filler, such as SilMix); about 0 to 25 wt % (e.g., about 5, 10,15, 20, or 25 wt %—most preferably about 10 to 20 wt %) other filler(e.g., glass, such as an unmodified glass filler); and about 0.05 to 5wt % (e.g., about 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or5.0 wt %) of the chemical cure or dual chemical/light curing system. Forexample, the chemical cure system may comprise about 0.05 to 1.0 wt %(most preferably about 0.05 to 0.2 wt %)p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate and about 0.05 to1.0 wt % (most preferably about 0.09 to 0.2 wt %) Lamoreaux's catalyst.

As another example, the biomaterial composition comprises about 30 to 60wt % (e.g., about 30, 35, 40, 45, 50, 55, or 60 wt %—most preferablyabout 35 to 50 wt %) organosilicon monomer (e.g., silorane co-monomer,such as SilMix) and about 0 to 80 wt % (e.g., about 5, 10, 15, 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 wt %—most preferably about45 to 65 wt %) filler (e.g., DY5 filler modified with ECHE, 3TOSU, or1TOSU); and about 0.05 to 5 wt % (e.g., about 0.05, 0.06, 0.07, 0.08,0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.3, 1.4,1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6,3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0 wt %) of the chemical cure or dualchemical/light curing system. For example, the dual chemical/lightcuring system may comprise about 0.05 to 1.0 wt % (preferably about 0.3to 0.8 wt %) Lamoreaux's catalyst and a photoinitiation systemcomprising about 1 to 5 wt % of an accelerator (e.g., about 3 wt % PIH),about 0.05 to 2 wt % photosensitizer (e.g., about 1 wt %camphorquinone), and 0.05 to 0.5 wt % electron donor (e.g., about 0.15wt % EDMAB).

As another example, the biomaterial composition comprises about 20 to 98wt % (e.g., about 30, 35, 40, 45, 50, 55, 60, 65, 60, 65, 70, 75, 80,85, 90, 91, 92, 93, 94, 95, 96, 97, 98 wt %—most preferably about 90 to98 wt % for the “neat” biomaterial composition) organosilicon monomer(e.g., silorane co-monomer, such as SilMix); about 0 to 80 wt % (e.g.,about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80wt %—most preferably about 45 to 65 wt %) filler (e.g., DY5 fillermodified with ECHE, 3TOSU, or 1TOSU); and about 0.05 to 5 wt % (e.g.,about 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, 0.9, 1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.4,2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0 wt %)of the chemical cure or dual chemical/light curing system. For example,the dual chemical/light curing system may comprise a mixture and acid(preferably a Bronsted acid), photoacid, and a photosensitizer. Theratio of the Bronsted acid to the photoacid is preferably between about3:1 to 1:3 by weight (e.g., about 3:1, 2:1, 1:1, 1:2, and 1:3). Theratio of the Bronstead acid to the photosensitizer is preferably about10:1 to 1:1 by weight (e.g., about 10:1, 8:1, 5:1, 3:1, and 1:1). In anexemplary aspect, the biomaterial composition may comprise a dualchemical/light cure system comprised of acetic acid, PIH, andcamphorquinone at a ratio of about 3:3:1 percent by weight, e.g., about3 wt % acetic acid, 3 wt % PIH, and 1 wt % camphorquinone (for a neatbiomaterial composition containing no filler) and 1.5 wt % acetic acid,1.5% PIH, and 0.5% camphorquinone (for a 50% filled biomaterialcomposition).

Each of the components of the composition of the present invention willnow be described in further detail.

Organosilicon Monomers

Various organosilicon monomers useful in the biomaterial compositions ofthe present invention are set forth in Chappelow, U.S. Published PatentApplication No. 2007/0072954; Weinmann et al., U.S. Pat. No. 6,908,953;Weinmann et al., U.S. Pat. No. 6,245,828 entitled “PolymerizableCompositions Based on Epoxides” and Bissinger et al., U.S. Pat. No.6,624,236 entitled “Cyclosiloxane-Based Cross-Linkable Monomers,Production Thereof in Polymerizable Materials;” Weinmann et al.,Siloranes in dental composites, Dent. Mater. 21(1) 68-74 (2005); Eick etal., Properties of silorane-based dental resins and compositescontaining a stress-reducing monomer, Dent. Mater. 23(8) 1011-1017(2007); all of which are incorporated by reference. Most preferredorganosilicon monomers are “siloranes,” which generally refer tosilicon-containing monomers having an oxirane (epoxide) and preferably asiloxane (e.g., Si—O bond or Si—O—Si—O).

A variety of organosilicon compounds with oxirane functionality werefirst synthesized and polymerized by Sato et al., JP Patent No. 51033541(Sep. 20, 1976). Similar compounds were studied by Crivello and others.See Crivello et al., European Patent No. 574264 (1993); and Crivello etal., European Patent No. 412430 (1991), which are incorporated byreference. Most preferred are multifunctional cycloaliphaticsiloxane-based oxiranes. Exemplary organosilicon monomers useful forforming the dental matrix resins of the present invention includedi-3,4-epoxy cyclohexylmethyl-dimethyl-silane (DiMe-Sil; R^(N)349660-80-6; MF, _(C16H28O2)Si; 95% purity),1,4-bis(2,3-epoxypropyloxypropyl-dimethylsilyl)benzene (Phen-Glyc; RN18715-54-3; MF, C₂₂H₃₈O₄S_(i2); 97% purity), and1,3,5,7-tetrakis(ethy^(l) cyclohexane epoxy)-1,3,5,7-tetramethylcyclotetrasiloxane (CYGEP; RN 121225-98-7; MF, C₃₆H₆₄O₈S_(i4); 98%purity), all available from 3M-ESPE (St. Paul, Minn.). Exemplarysiloranes are set forth in Weinmann et al., Volume shrinkage of a newfilling material based on siloranes, J. Dent. Res. 80(SI) 780 Abstr. No.2027 (2001); Weinmann et al., Comparative testing of volumetricshrinkage and sealing of silorane and methacrylate filling materials, J.Dent. Res. 81(SI-A) 417 Abstr. No. 3382 (2002); Dede et al., Comparisonof two ways to determine polymerization shrinkage of composites, J.Dent. Res. 83(SI-A) Abstr. No. 0057 (2004); Guggenberger et al.,Exploring beyond methacrylates, Am J Dent. 13 82D-84D (November 2000);Schwekl, The induction of gene mutations and micronuclei by oxiranes andsiloranes in mammalian cells in vitro, J. Dent. Res. 83(1) 17-21(January 2004); Eick et al., Stability of silorane dental monomers inaqueous systems, J. Dent. 34(6) 405-410 (2006), Watts, Shrinkage-StressKinetics of Silorane versus Dimethacrylate Resin-Composites, 12Baltimore Convention Center 322-323 (Abstract) (March 2005); and Klettkeet al., U.S. Pat. No. 6,779,656, which are all incorporated byreference.

Combinations of organosilicon monomers may also be utilized in thebiomaterial compositions of the present invention. For example, SilMixis comprised of a 1:1 w/w (2:1 mol/mol) ratio ofmethylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane I(“PHEPSI”) and2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtaneII (“CYGEP”) produced by 3M-ESPE (St. Paul, Minn.). The structuresSilMix compounds are shown below:

The organosilicon monomers used in the biomaterial compositions of thepresent invention are preferably prepared at purities greater than 90%,and most preferably greater than 95% as determined by ¹H NMRspectroscopy.

The organosilicon monomers preferably comprises about 20 to 98 wt %(e.g., about 20, 30, 40, 50, 60, 70, or 80%), and in some aspects, morepreferably about 40 to 60 wt % of the composition. Furthermore, asdiscussed below, the monomers may be pre-polymerized prior to additionto the composition so that the biomaterial composition comprises bothunpolymerized monomers and pre-polymerized polymer prior topolymerization. Typically, the ratio of unpolymerized monomers (e.g.,SilMix co-monomer) to polymer (e.g., pre-polymerized SilMix) is about1:5 to 5:1 (e.g., about 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, or 5:1,or some range therebetween). For biomaterial compositions containingpre-polymerized organosilicon monomers, the polymer is preferablycrushed or ground to a particle size (typically irregular in shape) ofabout 0.5 to 15 μm (e.g., 0.5, 1, 3, 5, 7, 9, 11, 13, or 15 μm, or somerange therebetween) with a number average size of about 2 μm. Thepre-polymerized organosilicon monomer essentially functions as a fillerin the overall composition.

Cure/Initiation Systems

The biomaterial compositions of the present invention also include achemical cure/initiation system or a dual chemical/light curing system.

1. Chemical Cure/Initiation System

In one aspect, the chemical curing system comprises a hydrosilationcatalyst which may be used to effect the addition of the ethylenicallyunsaturated epoxide or epoxide/organic mixture. Preferred catalysts arethose taught by Lamoreaux in U.S. Pat. Nos. 3,917,432; 3,197,433; and3,220,972, which are all hereby incorporated by reference. The platinumcatalyst disclosed in the patents to Lamoreaux is a complex formed fromchloroplatinic acid with up to about 2 moles per gram of platinum of amember selected from the class consisting of alcohols, ethers,aldehydes, and mixtures of the above. This catalyst will sometimes bereferred to herein as the “Lamoreaux catalyst.”

In a preferred aspect, the chemical curing system comprises aLamoreaux's catalyst which involves either PtCl₂ with aldehyde and etherlinkages derived from octanol. This catalyst was synthesized fromchloroplatinic acid H₂PtCl₆. using an adapted procedure by Lamoreaux,U.S. Pat. No. 3,220,972, which is incorporated by reference.

In one aspect, Lamoreaux's catalyst may be prepared by heating thereaction mixture to 70° C. at 25 mm Hg for 40 hours as discussed in thepatent references. In another aspect, Lamoreaux's catalyst may beprepared by heating the reaction mixture (chloroplatinic acidhexahydrate and octanol (98%) combined in a 1:7 mole ratio) to 50 to 55°C. under vacuum at 0.01 mm Hg for about 40 to 42 hours. After that time,the solution was filtered and washed with hexanes. The filtrate wasplaced under vacuum (0.01 mm Hg) at room temperature for about 8 to 12hours. The resulting liquid was stored under inert atmosphere in therefrigerator.

Further, other organometallic catalysts, such as those containingruthenium, rhodium, iridium, palladium, platinum, iron, osmium, cobalt,molybdenum, tungsten, nickel, copper, gold, silver, zirconium, andtitanium (most preferably Pt and/or Rh) are also possibilities forchemical curing. For example, for platinum-based catalysts, Wilkinson'scatalyst, Speier's catalyst, and Karstedt's catalyst may also beemployed, while Grubb's catalyst may be a suitable ruthenium-basedcatalyst.

The chemical curing system may optionally contain an accelerator. Apreferable accelerator is a photoacid, such as those described inAkizumi et al., U.S. Published Patent Application No. 2011/0172323,which is incorporated herein by reference. Most preferred acceleratorsare aryl-based iodonium salts, in particular a phenyl iodonium salt.Examples of such accelerators include, but are not limited to,(4-n-octyloxyphenyl)phenyliodonium hexafluoroantimonate (“PIH”), whichmay be obtained from GE Silicones under number 479-2092C;[4-(2-hydroxytetradecyloxyphenyl)]phenyliodonium hexafluoroantimonate(CD 1012), which may be obtained from Sartomer under the trade nameSarCat CD-1012 or from Gelest under the trade name OMAN072;[4-1-methylethyl)phenyl](4-methylphenyl)iodoniumtetrakis(pentafluorophenyl)borate(1-) (RH02074), which may be obtainedfrom Rhodia, Inc., under the trade name Rhodorsil Photoinitiator 2074;and combinations thereof. See also, similar compounds discussed inYamtao et al., WO 2002/046507, which is incorporated by reference.Although such accelerators have been traditionally used in lightinitiated polymerization systems, they also may be used in thechemical-initiated polymerization composition of the present invention.The mechanism by which the photoacid (e.g., PIH) reacts with theorganometallic catalyst (e.g., Lamoreaux's catalyst) to permitpolymerization in the dark when using this exemplary chemical curingsystem of the present invention is not known.

It will be appreciated that chemical curing system does not require aphotosensitizer or reaction promoter (although such compounds couldoptionally be included in the composition).

The chemical curing system preferably comprises about 0.05 to 2 wt %(e.g., 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 wt %)of the biomaterial composition. For example, the chemical cure systemmay comprise about 0.1 to 1.0 wt % of the photoacid (e.g., about 0.05 to0.4 wt %, preferably about 0.05 to 0.2 wt %, ofp-(octyloxyphenyl)phenyliodonium hexafluoroantimonate) and about 0.05 to1.0 wt % organometallic catalyst (e.g., about 0.1 to 0.4 wt %,preferably about 0.09 to 0.2 wt % Lamoreaux's catalyst).

2. Dual Chemical/Light Cure/Initiation System

In another aspect, the biomaterial compositions of the present inventioncomprise a dual chemical/light cure system. One exemplary dualchemical/light cure system comprises a mixture of a chemical curingagent (such as an acid or one of the organometallic catalysts referencedherein), along with an accelerator (see examples above),photosensitizer, and/or reaction promoter.

Chemical Curing Agent (e.g. Acetic Acid Containing Systems)

The dual chemical/light cure system may include an acid. In the presentinvention, various Lewis aids, Bronsted acids, and super acids wereinvestigated. The acids investigated included hydrochloric acid, aceticacid (“AA”), phosphoric acid, sulfuric acid, hydrobromic acid,hydroiodic acid, trichloroacetic acid, trifluoroacetic acid,p-toluenesulfonic acid, boron trifluoride, aluminium chloride, tin (IV)chloride, titanium chloride, pentafluoroproprionic acid, triflic acid,hexafluorophosphoric acid (“HFPA”), ethyl triflate, potassiumt-butoxide, and mixtures thereof (e.g., AA/HFPA, phosphoric acid/TiCl₄,phosphoric acid/triflic acid, phosphoric acid/p-toluene sulfonic acid,and phosphoric acid/trifluroacetic acid).

The preferred acid investigated is acetic acid. Thus, in one aspect, thepreferred acid is a weak/mild monoprotic acid which is nontoxic andbiocompatible. The acid preferably has a pKa between about 3 and 6(e.g., 3, 4, 5, or 6), exhibits low volatility, and is soluble in theorganic monomers being polymerized.

Photosensitizer

The dual curing system also preferably includes one or morephotosensitizers. Exemplary photosensitizers are disclosed in Chappelowet al., U.S. Pat. No. 6,653,486, which is incorporated by reference.Suitable sensitizers include compounds in the following categories:ketones, coumarin dyes (e.g., ketocoumarins), xanthene dyes, acridinedyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes,aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons,p-substituted aminostyryl ketone compounds, aminotriaryl methanes,merocyanines, squarylium dyes and pyridinium dyes. Ketones (e.g.,monoketones or alpha-diketones), ketocoumarins, aminoarylketones, andp-substituted aminostyryl ketone compounds are preferred sensitizers.For example, such photosensitizers include, but are not limited to as2,2-, 4,4- or 2,4-dihydroxybenzophenone, di-2-pyridyl ketone,di-2-furanyl ketone, di-2-thiophenyl ketone, benzoin, fluorenone,chalcone, Michler's ketone, 2-fluoro-9-fluorenone, 2-chlorothioxanthone,acetophenone, benzophenone, 1- or 2-acetonaphthone, 9-acetylanthracene,2-, 3- or 9-acetylphenanthrene, 4-acetylbiphenyl, propiophenone,n-butyrophenone, valerophenone, 2-, 3- or 4-acetylpyridine,3-acetylcoumarin and the like. Suitable diketones includearalkyldiketones such as anthraquinone, phenanthrenequinone, o-, m-, andp-diacetylbenzene, 1,3-, 1,4-, 1,5-, 1,6-, 1,7- and1,8-diacetylnaphthalene, 1,5-, 1,8- and 9,10-diacetylanthracene, and thelike. Suitable alpha-diketones include 2,3-butanedione,2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione,3,4-heptanedione, 2,3-octanedione, 4,5-octanedione, benzyl, 2,2′-3,3′-and 4,4′-dihydroxylbenzyl, furyl, di-3,3′-indolylethanedione,2,3-bomanedione (camphorquinone), biacetyl, 1,2-cyclohexanedione,1,2-naphthaquinone, acenaphthaquinone, and the like.

A preferred photosensitizer is an alpha-dicarbonyl compound. Examples ofspecific photosensitizers that may be used in the composition of thepresent invention include, but are not limited to, (+/−) camphorquinone,which may be obtained from Aldrich under the number 12,489-2 with a 97%purity; 2-chlorothioxanthen-9-one (“CTXO”), which may be obtained fromAldrich C7-240-4; and combinations thereof.

Reaction Promoter (Electron Donor)

Another preferred component of the dual chemical/light curing system isone or more electron donor compounds, which functions as a reactionpromoter. A class of donor compounds that may be useful in the inventivesystems may be selected from some of the electron donors described inChappelow et al., U.S. Pat. No. 6,653,486 and Palazzotto et al., U.S.Pat. No. 5,545,676, which are both incorporated by reference. Preferredelectron donor compounds include substituted amines, e.g., ethyldimethylaminobenzoate. The preferred electron donor that may be used inthe composition of the present invention include, but are not limitedto, ethyl p-dimethylaminobenzoate (“EDMAB”), which may be obtained fromAcros under number 11840-1000 at 99+% purity;4,4′-bis(diethylamino)benzophenone (“BDEAB”), which also may be obtainedfrom Acros under number 17081-0250s at 99+% purity; and combinationsthereof.

The dual chemical/light curing system preferably comprises about 0.05 to5 wt % (e.g., 0.05, 0.06, 0.07, 0.08, 0.9, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or5.0 wt %) of the biomedical composition.

Exemplary Dual Chemical/Light Curing Systems

In exemplary embodiments, the dual chemical/light curing system maycomprise 0.05 to 0.2 wt % (preferably about 0.3 to 0.8 wt %) Lamoreaux'scatalyst and a photoinitiation system comprising about 1 to 5 wt % of anaccelerator (e.g., about 1, 1.5, 2, 2.5, 3. 3.5, 4, 4.5 or 5 wt %,preferably about 3 wt % PIH), about 0.05 to 2 wt % photosensitizer(e.g., about 0.05, 1, 1.5, 2 wt %, preferably about 1 wt %camphorquinone), and 0.05 to 0.5 wt % electron donor (e.g., 0.05, 0.1,0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 wt %, preferably about 0.15wt % EDMAB).

In another exemplary aspect, the dual chemical cure system comprises anacid (e.g., acetic acid), a photosensitizer (e.g., camphorquione), and aphotoacid (e.g., PIH). The ratio of the Bronsted acid to the photoacidis preferably between about 3:1 to 1:3 by weight (e.g., about 3:1, 2:1,1:1, 1:2, and 1:3). The ratio of the Bronstead acid to thephotosensitizer is preferably about 10:1 to 1:1 by weight (e.g., about10:1, 8:1, 5:1, 3:1, and 1:1). For example, the composition may comprisea dual chemical/light cure system comprised of acetic acid, PIH andcamphorquinone at a ratio of about 3:3:1 percent by weight. For example,the composition may comprise about 1.5 wt % acetic acid, 1.5% PIH, and0.5% camphorquinone (for a 50% filled composition). The percentage byweight is preferably 3:3:1 of AA:PIH:CQ.

Fillers

The biomaterial compositions may further comprise one or more fillers.These fillers can possess a variety of morphologies such as, but notlimited to, needles, rods, particulate, flakes, plates, cylinders, longfibers, whiskers, or spherical particles. In some embodiments that maybe preferred, the filler is comprised of particles with an averageparticle size which is in the sub-micron or nanoparticle range, e.g.,less than about 1.0 μm. Exemplary particle sizes are about 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500,600, 700, 900, or 1000 nm or some range therebetween.

Given the appropriate interactions and dispersion qualities, particlesize may be a critical factor in that nanoparticles can produce dramaticchanges in the mechanical properties of the composition as compared tomicrometer sized fillers at comparable volume loading to analogousnanoparticle composites. For example, improvements in tensile strengthand modulus of five- and seven-fold may be obtained for compositescontaining only 1.5% nanoclay particles. Similar low loadings withresulting increased properties have been reported elsewhere.Surprisingly, higher concentrations of nanoparticles made little furtherimprovement. Improved strength and wear properties at low filler volumeloading are anticipated if the particles are not subject to beingablated from the matrix, i.e., are prevented from discreet particleablation by covalent bonding of the particles into the polymer matrix.

The filler may be comprised of an inorganic or organic material, whichmay be bioactive. In certain embodiments, the filler is comprised of aninorganic material.

Suitable fillers may be particulate or fibrous fillers with sizes in thenanoparticle to microparticle range. Fillers should be capable of beingcovalently bonded to the resin matrix itself or to a coupling agent thatprovides bonding to the filler and then the surrounding resin matrix.Examples of suitable filling materials include but are not limited toamorphous silica; spherical silica; colloidal silica; clays; bariumglasses; quartz; ceramic fillers; silicate glass; hydroxyapatite;calcium carbonate; fluoroaluminosilicate; barium sulfate; quartz; bariumsilicate; strontium silicate; barium borosilicate; bariumboroaluminosilicate; strontium borosilicate; strontiumboroaluminosilicate; bio active glass; dental glass ionomer filler;silicate or phosphate based glass fibers; lithium silicate; ammoniatedcalcium phosphate; deammoniated calcium phosphate; calcium tungstate;alumina; zirconia; tin oxide; zinc oxide; calcium oxide; magnesiumoxide, potassium oxide, barium oxide yttrium oxide, bismuth compoundssuch as bismuth oxychloride and bismuth oxide; polymer powders such aspolymethyl methacrylate, polystyrene, and polyvinyl chloride; titaniumdioxide; bound and nano structured silica fillers as set forth in U.S.Pat. No. 6,417,246, which is hereby incorporated by reference; densifiedand embrittled glass fibers or particles as set forth in U.S. Pat. Nos.6,013,694 and 6,403,676 which are hereby incorporated by reference;fibrous material and one or more forms of surface-modifying particlesbonded thereto as set forth in U.S. Pat. No. 6,270,562 which is herebyincorporated by reference; polyhedral oligomeric silsesquioxane fillersas set forth in U.S. Pat. No. 6,653,365 which is hereby incorporated byreference; nanostructures such as POSS™ (polyhedral oligomericsilsesquioxane) supplied by Hybrid Plastics; and combinations of all thefillers mentioned. Preferred fillers include titanium oxide and/orcalcium phosphate since these materials help promote mineralization andbone adhesion. Composition of the macro and micro fillers will not beidentical or perhaps even similar. Nanoparticles will be typically highpurity, high strength whiskers/rod/fibers/platelets, while themacrofiller will typically be a silica-based ally glass with additiveelements for strength and hardness.

In another aspect, examples of suitable fillers include, but are notlimited to, barium glass, barium-boroaluminosilicate glass, sodiumborosilicate, silica, 45S5 glass, bioactive glass, ceramics,glass-ceramics, bioactive synthetic combeite glass-ceramic, e-glass,s-glass, iron phosphate, or combinations thereof. The most preferredfillers are yttria alumino silicate (e.g., DY5; see table below) andbarium boroaluminosilicate (e.g., M12, see table below), and alumina orzirconia nanorods.

Preferred glass fillers can be made by either melting batches (M-seriesand alkali-containing DY-series) or by sintering batches andspheroidization of the sinter (alkali-free DY-series). Thesinter/spheroidization process was used for batches that melted above1550° C. The nominal chemical composition and n_(d) of the M-seriesglasses are given in Table 1 below. The nominal chemical composition andn_(d) of the DY-series glasses are listed in Table 2 below. The n_(d) ofthe glasses varied from 1.48 to 1.56 depending on composition, a rangeof values which is needed for reinforcing blue-light (440 nm)-curablecomposites.

TABLE 1 Nominal Weight Percent Composition and Refractive Index ofM-Series Filler Code Li₂O Na₂O K₂O MgO BaO CaO Y₂O₃ ZrO₂ M1 3 0 0 2 9 03 0 M2 3 0 0 2 9 0 3 0 M3 3 0 0 2 9 0 0 0 M4 3 0 0 2 9 0 3 0 M5 0 1 0 80 0 0 9 M6 0 1 0 2 0 22 0 5 M7 0 10 0 1 0 6 0 22 M8 0 6 8 0 2 6 0 5 M9 05 6 0 0 0 0 5 M10 3 0 0 2 9 0 3 0 Filler Code Yb₂O₃ ZnO TiO₂ B₂O₃ Al₂O₃SiO₂ AlF₃ n_(d) M1 0 0 0 58 14 8 3 1.53 M2 0 0 0 29 14 37 3 1.52 M3 3 00 29 14 37 3 1.52 M4 0 0 0 58 0 22 3 1.53 M5 0 0 0 0 21 61 0 1.52 M6 0 00 7 11 52 0 1.56 M7 0 0 0 3 4 54 0 1.56 M8 0 5 0 0 2 66 0 1.52 M9 0 7 48 4 61 0 1.52 M10 0 0 0 58 14 8 3 1.52

TABLE 2 Nominal Weight Percent Composition and Refractive Index ofDY-Series Glasses Filler Code Y₂O₃ Yb₂O₃ Al₂O₃ SiO₂ Na₂O n_(d) DYb1 0 2321 56 0 1.55 DY2 1 0 9 90 0 1.48 DY3 3 0 9 88 0 1.48 DY4 15 0 21 64 01.56 DY5* 15 0 5 80 0 1.52 DY6 15 0 15 70 0 1.53 DY7 14 0 14 67 5 1.52DY8 14 0 14 62 10 1.51 DY9 13 0 13 59 15 1.53 DY10 0 23 21 56 0 1.52*Vickers microhardness 6.2 GPa (739 ± 22 kg/mm²)

Nanoparticles assist cement formulation, reinforcing and strengtheningthe interstitial domains within the composition, obtaining radiopacitywhen not obtained via the macrofiller, and hardening the surface againstwear by increasing the filler volume concentration. While spherical orirregular nanoparticles are used in current formulations,whisker/nanorods and/or clay platelets may also be used for interstitialstrengthening of the macroparticle filled composite where obtained atlow filler volume loading. An increased aspect ratio is important tomechanical strength, minimization of crack initiation, and can supportmineralization by osteoblast cells though spherical or irregularnanoparticles that can also be utilized to reinforce the interstitialcomposite so long as a suitable surface modification or coupling agentis utilized to strengthen bone across the polymer-particle interface.Clay/nanowhisker/nonrod dimensions are preferred that have aspect ratiosgreater than 10:1 up to about 100:1. Clays include montmorillonites andnanowhisker/nanorod includes boehmite, alumina, zirconia,yttria-stabilized zirconia, titania, calcium phosphate, or hydroxylapatite.

Surface modifications can be used to control interparticle association,dispersion viscosity, and reactivity with the surrounding matrix. In oneaspect, nanospheres or nanofillers, typically up to 500 nm in length and30 nm in diameter may be used. Normal, glass filled systems can also beused for dispersion quality, flexural strength, hardness, internalpolymerization stress, efficiency of cure, and cell toxicity of theresulting composite. Compositions of the nanofibers include aluminananospheres and nanorods, which have produced improved tensile andflexural strength. While alumina has provided remarkable propertyimprovements, zirconium-yttrium oxide fiber synthesis, whose fibers havebetter pH stability compared to alumina, may also be used. Nanorods willbe synthesized via gel formation followed by chemically templating inconventional oven or by autoclave, as appropriate for the desiredgeometry.

Montmorillonite clays are the most common member of the smectite clayfamily having plate-like primary particles that possess an anionicsurface with ionically bound cations to maintain surface chargeneutrality. Natural montmorillonite clay has sodium counterions on thesurface; however, these sodium atoms can be ion-exchanged with otherinorganic or organic ions to change the surface chemistry of the clayparticles. In addition, natural montmorillonite clay particles arestacked upon one another due to the charge-charge interaction betweenthe clay platelets. Once the counterion is exchanged for an organic ionor group, the replacement facilitates the separation of the claylattice, especially when penetrated by solvents, monomer or polymerchains, called intercalation. The particles may then be furtherdispersed into discreet nanoplatelets resulting in what is called anexfoliated clay material. Upon synthesis of exfoliated structures, largemechanical property improvements of a composite compared to neat polymerproperties are obtained at rather low clay filler concentration levels.

Such fillers include, but are not limited to, a hydroxyapatite in theform of hollow microspheres or biocompatible, biodegradable glass. Themicrospheres of hydroxyapatite could be used to contain and act ascarriers for antibiotics. Other components of the composites that couldbe delivered within the hydroxyapatite microspheres include growthfactors such as bone morphogenetic proteins (“BMPs), cartilage-derivedmorphogenic proteins (“CDMPs”), collagen, or small molecules that arebeing developed to promote bone growth through blood vessel formation.In one aspect, the growth factor is selected from the group consistingof TGFβ1, TGFβ2, TGFβ3, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8,BMP-9, CDMP-1, CDMP-2, or CDMP-3.

For silorane composites, good interfacial properties between polymerresin and fillers improve composite properties and performance. Thereare variables of group density and structure, which affect surfacewetting, reactivity, interfacial structure, and composite strength. Theinclusion of a surface coupling agent or ligand increases the criticalconcentration of particle fillers that can be added by enhancing surfacewetting and dispersion viscosity. Interfacial properties are even morecritical since the intended application requires immersion within aplasticizing, high-moisture environment. Interfaces between filler andresin matrix are prime locations for weakening through ingress ofmoisture. However, interfaces can be strengthened through surfacemodification of fillers resulting in greater mechanical properties toenable not only interaction, but also reaction with the surroundingpolymer matrix, including chain extension, between filler and polymermatrix. Several types of surface modifications may be used to improvestrength through development of covalent interface architectures duringcure. Surface modifications are produced through exposure to dilutesolutions to prevent multi-layer, weak, adsorbed structures and providebetter ligand access to filler surfaces. After washing particlesthoroughly of excess reagent, groups are quantified by thermogravimetricanalysis (TGA) for comparison to bare particles. Fourier transforminfrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS),and surface density calculated from weight loss using known particlesurface area and correcting for bulk and adsorbed water loss is used toanalyze the filler surface coating. Surface tension and wetting offiller powders is readily measured using tensiometry through theWashburn equation.

The filler typically is about 0, 5, 10, 15, 20, 25, 30, 40, 45, 50, 55,60, or 70 wt % (or some range therebetween) of the biomaterialcomposition.

TOSUs and TOSU-Like Compounds

TOSUs may optionally be added to the biomaterial compositions of thepresent invention. The TOSUs may be classified as1,5,7,11-tetraoxaspiro[5.5]undecanes or2,4,8,10-tetraoxaspiro[5.5]undecanes. The TOSUs may or may not have asilicon-containing moiety. The TOSUs are preferably a potentialexpanding monomer type. By using the TOSUs, the composition has thepotential of reducing the amount of polymerization stress of the totalformulation.

Various TOSUs are set forth in Chappelow, U.S. Published PatentApplication No. 2007/0072954; Chappelow et al., U.S. Pat. No. 6,825,364;Chappelow et al., U.S. Pat. No. 6,653,486; Chappelow et al., U.S. Pat.No. 6,658,865; Byerley et al., U.S. Pat. No. 5,556,896; Guest, U.S. Pat.No. 3,023,222l; Sadhir & Luck, Expanding Monomers: Synthesis,Characterization, and Applications, CRC Press, Boca Raton, Fla. (1992);Rokicki, Aliphatic cyclic carbonates and spiroorthocarbonates asmonomers, Prog. Polym. Sci. 25 259-342 (2000); Imai et al., JP28196665B2; and Porret et al., JP 03099086; which are all incorporatedby reference. An important synthetic precursor is3,9-diethyl-3,9-bis(allyloxymethyl)-1,5,7,11-tetraoxaspirol[5.5]undecane(DEBAOM-1,5,7,11-TOSU), and is a six-member ring spiroorthocarbonatethat is a liquid at room temperature. The vinyl groups on this moleculepermit the addition of a wide variety of reactive and unreactivefunctionalities by electrophilic and radical means. Thesefunctionalities can be both symmetric and asymmetric.

In one aspect of the present invention, TOSUs according to Formulas A1or A2 may be utilized in the biomaterial compositions:

wherein R₁ and R₃ are independently is alkyl, aryl, aralkyl, orhydrogen; and

wherein R₂ and R₄ are independently alkenoxy, alkenoxyalkyl, orsilicon-containing moiety selected from alkylsilyl, arylsilyl,arylalkylsilyl, alloxysilyl, aryloxysilyl, arylalkoxysilyl, alkylsiloxy,arylsiloxy, arylalkylsiloxy, alkoxysiloxy, aryloxysiloxy,arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl, arylalkysilylalkyl,alkoxysilylalkyl, aryloxysilylalkyl, arylalkoxysilylalkyl,alkylsiloxyalkyl, arylsiloxyalkyl, arylalkylsiloxyalkyl,alkoxysiloxyalkyl, aryloxysiloxyalkyl, arylalkoxysiloxyalkyl,alkylsilylalkoxy, arylsilylalkoxy, arylalkylsilylalkoxy,alkoxysilylalkoxy, aryloxysilylalkoxy, arylalkyloxysilylalkoxy,alkylsiloxyalkoxy, arylsiloxyalkoxy, arylalkylsiloxyalkoxy,alkoxysiloxyalkoxy, aryloxysiloxyalkoxy, and arylalkoxysiloxyalkoxy.

In another aspect, the TOSUs are characterized by Formulas A1 or A2wherein R₂ and R₄ are independently alkylsilylalkyl or alkylsiloxyalkyl.In one preferred aspect, R₂ and R₄ are independentlytrimethylsilylpropyl, trimethylsilylethyl, triethylsilylpropyl, ortriethylsilylethyl.

In still another aspect, the TOSU compounds according to Formula A1 orA2 are characterized such that R₁ and R₃ are independently is alkyl,aryl, aralkyl, or hydrogen; and wherein R₂ and R₄ are independentlyalkenoxyalkyl or alkylsilylalkyl. In still another aspect, R₂ and R₄ areindependently alkenyloxyalkyl selected from—(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂, and wherein m and n are independently 0,1, 2, 3, 4; or alkylsilylalkyl selected from trimethylsilylpropyl andtrimethylsilylethyl.

In another aspect, the TOSU compounds according to the Formula A2 arecharacterized such that R₁ and R₃ are independently alkyl, aryl,aralkyl, or hydrogen; and wherein R₂ and R₄ are independently alkenyl,alkenoxy, alkenoxyalkyl, or silicon-containing moiety selected fromalkylsilyl, arylsilyl, arylalkylsilyl, alloxysilyl, aryloxysilyl,arylalkoxysilyl, alkylsiloxy, arylsiloxy, arylalkylsiloxy, alkoxysiloxy,aryloxysiloxy, arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl,arylalkysilylalkyl, alkoxysilylalkyl, aryloxysilylalkyl,arylalkoxysilylalkyl, alkylsiloxyalkyl, arylsiloxyalkyl,arylalkylsiloxyalkyl, alkoxysiloxyalkyl, aryloxysiloxyalkyl,arylalkoxysiloxyalkyl, alkylsilylalkoxy, arylsilylalkoxy,arylalkylsilylalkoxy, alkoxysilylalkoxy, aryloxysilylalkoxyarylalkyloxysilylalkoxy, alkylsiloxyalkoxy, arylsiloxyalkoxy,arylalkylsiloxyalkoxy, alkoxysiloxyalkoxy, aryloxysiloxyalkoxy, andarylalkoxysiloxyalkoxy.

In another aspect, the TOSU compounds according to the Formula A1 or A2are characterized such that R₁ and R₃ are independently alkyl, aryl,aralkyl, or hydrogen; and wherein R₂ and R₄ are independently alkenyl,alkenoxyalkyl, and alkylsilylalkyl. In still a further aspect, R₂ and R₄are independently alkenyl selected the group consisting of—(CH₂)_(n)—CH═CH₂, and wherein n is independently 0, 1, 2, 3, 4; oralkenyloxyalkyl selected from —(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂, and whereinm and n are independently 0, 1, 2, 3, 4; or alkylsilylalkyl selectedfrom trimethylsilylpropyl and trimethylsilylethyl.

In another aspect, R₁, R₂, R₃, and R₄ are independently selected fromthe group consisting of alkyl, olefin-terminated alkyl,olefin-terminated alkyl ether, trimethylsilyl alkyl ether, andcyclohexyl.

For example, in one aspect, the TOSUs are selected from the groupconsisting of the following compounds:

3,9-Diethyl-3,9-bis(allyloxymethyl)-1,5,7,11-tetraoxaspirol[5.5]undecane(DEBAOM-1,5,7,11-TOSU) (Example 1 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

9-Bis(3-trimethylsilylpropyl)-1,5,7,11-tetraoxaspiro[5.5]undecane(BTMSP-1,5,7,11-TOSU) (Example 2 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

3,9-Bis(allyloxymethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(BAOM-2,4,8,10-TOSU) (Example 3 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

3,9-Bis(2-trimethylsilylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(BTMSE-2,4,8,10-TOSU) (Example 4 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

3,3-Diethyl-11,12-epoxy-1,5,7,16-tetraoxadispiro[5.2.5.2]hexadecane(DECHE-1,5,7,11-TOSU) (Example 5 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

3,9-Diethyl-3,9-bis(3-trimethylsilylpropyloxymethyl)-1,5,7,11-tetraoxaspiro[5.5]undecane(DEBTMSPOM-1,5,7,11-TOSU) (Example 6 of Chappelow, U.S. Published PatentApplication No. 2007/0072954)

(9-Allyloxymethyl-9-ethyl-1,5,7,11-tetraoxaspero[5.5]undec-3-ylmethyl)-dimethylphenyl-silane(AOME-TOSU-MDMPS)

Methyl[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-phenyl[3-(3,9,9-triethyl-1,5,7,11-tetraoxaspiro[5.5]undec-3-ylmethoxy)propyl]silane(MOB-HEP-TETOSU-MOPS)

For biomaterial compositions containing fillers, stress-reducingmonomers like TOSUs may be used for surface modification through theattachment of a surface-reactive ligand group, such as a pendant silylor phosphate, that is reactive with the filler oxide surface. Theorganic moiety provides wetting and dispersion, interfacial (cure)reactivity, and interfacial strength properties while adding thepotential to reduce internal stress in the composite. Since group lengthhas a direct effect on interfacial bond and thus composite strength, thetether length between the reactive group and the surface active ligandis one design aspect may be considered. See Wang et al., Dharani L R.Effect of interfacial mobility on flexural strength and fracturetoughness of glass/epoxy laminates, Journal of Materials Science 34(19)4873-4882 (1999); Schuman et al., Surface modified nanoparticles asenhanced fillers for dental polymer-particle composites, J Dent Res 89(2010); Schuman et al., Improved dielectric breakdown strength ofcovalently-bonded polymer-particle nanocomposites, Composite Interfaces,17, 719-731 (2010). For example, for{3-(9,9-diethyl,1,5,7,11-tetraoxa-spiro(5.5)undec-3-yl)propyl}-trimethoxysilane(“3TOSU”), a surface group density of about 26 Å2/group was obtained inreacting with glass particles or alumina nanorods, measured through TGAand also observed through XPS. Thus, addition of TOSUs (or compoundshaving analogous ring systems like the compounds shown below) to thesilorane and/or as filler particle surface treatment should improve themechanical properties of the silorane composite. The synthesis of(9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3-yl)methyl)trimethoxysilane(“1TOSU”) and(3-(9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3-yl)propyl)trimethoxysilane(“3TOSU”) is shown in the schemes below.

The TOSUs (or TOSU-like compounds) preferably comprises about 0 to 25%by weight of the biomaterial composition. For example, the TOSUs maycomprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, or 20 wt % (or some range therebetween) of the biomaterialcomposition.

In another aspect, filler(s) are combined with one or more TOSUs. Theoptional filler and optional TOSU is preferably selected from the groupconsisting of (1) crushed light initiated SilMix (pre-polymerizedSilMix); (2) DY5—yttria alumino-silicate; 15.0 wt % Y₂O₃, 5.0 wt %Al₂O₃, and 80 wt % SiO₂; (3) DY5 modified with2-(3,4-epoxycyclohexyl)-ethyl-trimethoxysilane (ECHE); (4) DY5 modifiedwith 3-(glycidyloxy)-propyl-trimethoxysilane (GPS); (5) DY5 modifiedwith 3TOSU(3-(9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3-yl)propyl)trimethoxysilane;(6) DY5 modified with 1TOSU((9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3yl)methyl)trimethoxysilane; (7) M12—barium boroaluminosilicate; 54.5 wt% SiO₂, 5.9 wt % Al₂O₃, 10.5 wt % B₂O₃, and 29.1 wt % BaO; (8) M12modified with ECHE ethylcyclohexylepoxide; (9) M12 modified with 3TOSU(3-(9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3-yl)propyl)trimethoxysilane;(10) M12 modified with 1TOSU((9,9-diethyl-1,5,7,11-tetraoxaspiro[5.5]undecan-3yl)methyl)trimethoxysilane;(11) clays, montmorillonite plates of aspect ratio between about 100 to300, surface modified with organic ammonium ions containing epoxy,hydroxyl, ether, ester, phosphate, allyl or vinyl functional groups, orsilanes (trichloro, trimethoxy, triethoxy, dichloromethyl,dimethoxymethyl, diethoxymethyl, chlorodimethyl, methoxydimethyl, orethoxydimethyl) containing a pendant epoxy, hydroxyl, ether, ester,phosphate, allyl or vinyl functional group; and (12) nanoparticles asspherical, nanofiber, nanowhisker, or nanorod—especially gamma aluminum,hydroxyapatite, calcium phosphate, zirconium, or titanium, with aspectratio in the range of about 1 to 200, preferably between 1 and 20, neator surface modified with organosilanes (trichloro, trimethoxy,triethoxy, dichloromethyl, dimethoxymethyl, diethoxymethyl,chlorodimethyl, methoxydimethyl, or ethoxydimethyl) containing a pendantepoxy, hydroxyl, ether, ester, phosphate, allyl or vinyl functionalgroup or surface modified with organophosphates containing a pendantepoxy, hydroxyl, ether, ester, allyl or vinyl functional group,including 1TOSU, 3TOSU, or a TOSU-phosphate surface active, ligandgroups.

The following examples are offered to aid in understanding the inventionand are not to be construed as limiting the scope thereof.

Example 1: Preparation of Exemplary Bone Cement Compositions

In this example, various biomaterials useful as bone cement compositionswere prepared. All samples were prepared at room temperature (about 20°C.) under yellow light (for the light-initiated systems and the dualchemical/light curing systems, but not the chemical curing systems) inorder to prevent premature polymerization. The samples will be referredto as either neat resins (no filler) or filled resin (may include one ormore fillers).

Each of the bone cement compositions comprised two silorane monomers,bis[2-(3 {7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane (PHEPSI)and2,4,6,8-tetrakis(2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl)-2,4,6,8-tetramethyl-1,3,5,7,2,4,6,8-tetraoxatetra-silocane(CYGEP). Both PHEPSI and CYGEP were prepared using adapted proceduresand used at purities greater than 95.8% as determined by ¹H NMRspectroscopy. See Aoki, U.S. Pat. No. 6,255,428; Crivello, The Synthesisand Cationic Polymerization of Multifunctional Silicon-Containing EpoxyMonomers and Oligomers, J. Polym. Sci. Part A: Polym. Chem. 32 683-697(1994). P1 comprises a chemical cure system comprising an organometalliccatalyst and an accelerator. P2 comprises a dual chemical/light curesystem comprising and organometallic catalyst and a photoinitiationsystem.

P1 comprises (A) co-monomer system SilMix (1:1 by weight of PHEPSI andCYGEP), between about 40 to 55 wt %; (B) photoacidp-(octyloxyphenyl)phenyliodonium hexafluoroantimonate, between about0.05 to 0.20 wt %; (C) Lamoreaux's catalyst, between about 0.09 to 0.2wt %; (D) filler DY5, between about 10 to 20 wt %; and (E) fillercrushed SilMix, between about 25 to 50 wt %. The following tableincludes several exemplary bone cement compositions that were prepared.

TABLE 3 Exemplary P1 formulations SilMix Pre-polymerized SiloraneCo-Monomer SilMix DY5 PIH LMC 0.5466 0.3500 0.1000 0.0014 0.0020 0.40000.4500 0.1472 0.0008 0.0020 0.4000 0.4500 0.1472 0.0008 0.0020 0.40000.3960 0.2000 0.0020 0.0020 0.4722 0.3997 0.1247 0.0017 0.0017 0.42420.4118 0.1618 0.0011 0.0011 0.4472 0.3500 0.2000 0.0020 0.0008 0.40000.3960 0.2000 0.0020 0.0020 0.4000 0.4500 0.1472 0.0020 0.0008 0.54720.3500 0.1000 0.0020 0.0008 0.4972 0.4000 0.1000 0.0008 0.0020 0.54780.3500 0.1000 0.0008 0.0014 0.4483 0.3994 0.1494 0.0014 0.0014 0.40000.3984 0.2000 0.0008 0.0008 0.4483 0.3994 0.1494 0.0014 0.0014 0.44720.3500 0.2000 0.0020 0.0008 0.4960 0.3500 0.1500 0.0020 0.0020 0.44720.3500 0.2000 0.0008 0.0020 0.5466 0.3500 0.1000 0.0014 0.0020 0.44830.3994 0.1494 0.0014 0.0014 0.4483 0.3994 0.1494 0.0014 0.0014 0.44600.4500 0.1000 0.0020 0.0020 0.4000 0.4500 0.1472 0.0020 0.0008 0.49780.3747 0.1247 0.0017 0.0011 0.4484 0.4500 0.1000 0.0008 0.0008 0.54780.3500 0.1000 0.0008 0.0014 0.4475 0.4247 0.1247 0.0017 0.0014 0.40000.3984 0.2000 0.0008 0.0008 0.4984 0.3500 0.1500 0.0008 0.0008 0.54720.3500 0.1000 0.0020 0.0008 0.4472 0.3500 0.2000 0.0008 0.0020 0.40000.3960 0.2000 0.0020 0.0020 0.4460 0.4500 0.1000 0.0020 0.0020 0.47220.3747 0.1497 0.0017 0.0017 0.4483 0.3994 0.1494 0.0014 0.0014 0.49840.3500 0.1500 0.0008 0.0008 0.4484 0.4500 0.1000 0.0008 0.0008 0.49600.3500 0.1500 0.0020 0.0020 0.4484 0.3747 0.1747 0.0011 0.0011 0.49720.4000 0.1000 0.0008 0.0020

P2_DY5_mod_ECHE (“P2A”) comprises (A) co-monomer system SilMix (1:1 byweight of PHEPSI and CYGEP), between about 35 to 55 wt %, %; (B)Lamoreaux's catalyst, between about 0.3 to 0.8 wt %; (C) a lightinitiation system comprising about 3.0 wt %p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate, about 1.0 wt %camphorquinone, and about 0.15 wt % ethyl 4-dimethylaminobenzoate; and(D) a filler ECHE modified DY5, between about 45 to 65 wt %.

P2_DY5_mod_3TOSU (“P2B”) comprises (A) co-monomer system SilMix (1:1 bywt of PHEPSI and CYGEP), between about 35 to 55 wt %; (B) Lamoreaux'scatalyst, between about 0.3 to 0.8 wt %; (C) a light initiation systemcomprising about 3.0 wt % p-(octyloxyphenyl)phenyliodoniumhexafluoroantimonate, about 1.0 wt % camphorquinone, and about 0.15 wt %ethyl 4-dimethylaminobenzoate; and (D) a filler 3TOSU modified DY5,between about 45 to 65 wt %.

P2_DY5_mod_TOSU (“P2C”) comprises (A) co-monomer system SilMix (1:1 bywt of PHEPSI and CYGEP), between about 35 to 55 wt %; (B) Lamoreaux'scatalyst, between about 0.3 to 0.8 wt %; (C) a light-initiation systemcomprising about 3.0 wt % p-(octyloxyphenyl)phenyliodoniumhexafluoroantimonate, about 1.0 wt % camphorquinone, and about 0.15 wt %ethyl 4-dimethylaminobenzoate; and (D) a filler 1TOSU modified DY5,between about 45 to 65 wt %.

The components of the exemplary inventive formulations are mixedtogether in order to indicate polymerization. In a preferred aspect, allof the components except the Lamoreaux's catalyst are first mixedtogether in a suitable mixing device (such as a mixing cup). The desiredamount of Lamoreaux's catalyst is added and then the combined mixture isfurther mixed.

For comparative purposes, in some instances, the inventive formulationswere compared to those of conventional PMMA-based Simplex P Bone Cement(Stryker Homedica Osteonics). The first powder component is a mixture ofpolymethyl methacrylate (PMMA) (15.0%), methylmethacrylate-styrene-copolymer (75.0%), and barium sulfate (10.0%). Thesecond component of Simplex P bone cement is a liquid monomer containingmethyl methacrylate monomer (97.4%), N,N-dimethyl-p-toluidine (2.6%) andhydroquinone (75±15 ppm). The two components are mixed at a ratio of 2 gpowder to 1 mL liquid monomer to initiate the free-radicalpolymerization process.

Example 2: Mechanical Testing

Polymerization Stress

The bone cement compositions of the present invention will be tested forpolymerization stress. Two glass rods are placed 1 mm apart on the Bosemechanical testing instrument. Strain during testing will be heldconstant, less than 1.0 μm deflection, during polymerization. The peakload during polymerization will be used to calculate polymerizationstress as generally described in Eick et al., Properties ofsilorane-based dental resins and composites containing a stress-reducingmonomer, Dent Mater 23(8) 1011-1017 (2007), which is incorporated byreference.

Maximum Exotherm Temperature

Exotherm temperature was measured using a K-type thermocouple (Omega,Stamford, Conn.) affixed to a glass slide and slightly bent so that thetip of the thermocouple was positioned in the center of an acetal resin(Delrin®) washer (McMaster-Carr, Aurora, Ohio), which was also affixedto the glass slide with lab tape. Each composite formulation (0.6 g) wasmounded to completely cover the tip of the thermocouple. The sample wasthen irradiated (12 mm diameter tip, 450 mW/cm² (Cure Rite, DentsplyCaulk, Milford, Del.) at a distance of 3 mm) using a dental curing lamp(3M XL3000, St. Paul, Minn.) for two minutes. Specimens were inspectedafter testing, and results were excluded from further study if the tipcontacted the glass slide or was not entirely covered with thecomposite. Temperature data were recorded using a data logger (OM-PLTC,Stamford, Conn.) at 1 Hz for 30 minutes post-irradiation. Handling timewas defined as the time between initiation and when the exotherm reachedhalf of its peak temperature.

Handling Properties/Handling Time

The handling properties generally refer to the time from addition ofcatalyst or irradiation until one cannot manipulate the material. Thatis, handling time refers to the length of time the material can bemanipulated between mixing and polymerization to allow for placement inthe body. Bone cement consistently reaches dough time around 1.9 mmpenetration (about 9 minutes post-mixing). Curing time occurs whenpenetration is 0.0 mm (about 15 minutes).

Handling properties will be measured with a penetrometer. Timing willstart as the monomer (0.75 g) is mixed and placed in an aluminum washer(12.7 mm diameter, 2.5 mm deep). Penetration measurements (mm) will betaken periodically with a mass of 49.2 g applied to the penetrometercone for 5 seconds. This test will provide viscosity, and curing, dough,and manipulation time.

Flexural Strength and Modulus

The bone cement compositions of the present invention will be tested forflexural strength. Flexural specimens (25 mm×2 mm×2 mm) were formed inborosilicate glass tubes (VitroCom, Mountain Lakes, N.J.) coated withsilicone spray mold release (Mark V Laboratory, East Granby, Conn.) asper ISO specification 4049. A pipette was used to fill the molds withresin. The specimen was irradiated (12 mm diameter tip, 450 mW/cm² (CureRite, Dentsply Caulk, Milford, Del.) at a distance of 3 mm) using adental curing lamp (XL3000; 3M, St. Paul, Minn.) for two minutes alongthe top surface at three consecutive regions for 40 seconds each, 40seconds in a scanning motion along the bottom of the glass mold, andthen the specimen was removed from the glass. The method ofphotoinitiating specimens and induction of any overlapping regions havebeen shown to not have an effect on flexural properties. The specimenswere stored in phosphate buffered saline (PBS), at 23±1° C., for 24hours, after which, the specimen was loaded, until fracture, at adisplacement rate of 3.7 mm/min in a four-point bend fixture with asupport span of 20 mm on a BOSE mechanical tester (EnduraTEC ELF 3300,Eden Prairie, Minn.). Specimens with visible surface flaws, bubbles, orundistributed filler particles were excluded from the study. Theresulting stress-strain curve was used to determine flexural strength(σ_(B)) and flexural modulus of elasticity (E_(B)). The following twoequations were used to calculated stress (Eq 1) and strain (Eq 2). Theresulting stress-strain curve was used to determine flexural yieldstrength and flexural modulus of elasticity.

$\sigma = \frac{{load} \times {load}\mspace{11mu}{span}}{{specimen}\mspace{14mu}{width} \times \left( {{specimen}\mspace{14mu}{thickness}} \right)^{2}}$$ɛ = \frac{5.4 \times {displacement} \times {specimen}\mspace{14mu}{thickness}}{{load}\mspace{14mu}{span}^{2}}$

Compressive Strength

The bone cement compositions of the present invention will be tested forcompressive strength. Cylindrical specimens (6 mm diameter=12 mm height)were formed in a metal mold coated with silicone spray mold release asper ISO specification 4049. A pipette was used to fill the mold andcomposite formulations were either light-irradiated for 2 minutes ateach end of the cylinder for photoinitiated materials, or allowed topolymerize for 30 minutes for chemically initiated materials. Thecylinders were then removed from the molds and stored in PBS, at 23+/−1°C., for 24 hours, after which specimens were loaded until fracture at adisplacement rate of 20 mm/min between two smooth platens incompression. Specimens with visible surface flaws, bubbles, orundistributed filler particles were excluded from the study. Theresulting peak load prior to failure was used to calculate compressivestrength.

TABLE 4 Range of properties for P1 and P2 (P2A, P2B, P2C). Desired ISO5833 P1 P2 properties Standard Polymerization stress — — ≦1.0 (MPa)Exothermicity (° C.) 25-30 26 ± 0.5 ≦45 ≦90 Handling time (mins)  8-10 8-10 ≦20 3-15 Intrusion (mm) — — ≧2 Flexural modulus (GPa) 1.5-1.72.2-3.5 ≧1.8 Flexural strength (MPa) 22-33 25-60 ≧50 Compressivestrength — 68-77 ≧70 (MPa) Cytotoxicity (% cell death) 17% — ≦20%

Example 3: Cytotoxicity on Neat Dual Cure SilMix

In this example, the objective was to determine the bone cell growth onchemically cured silorane resins using a polymerization systemcontaining acetic acid as a proton donor plus exposure to halogen lamp.The compositions are described in Table 5. Solid resin discs (9 mmdiam×0.5 mm thick) (n=12) were yellow and transparent. Discs passed theGNT and were delivered in a closed plastic container. The discs wereyellowish transparent and were used as received (no UV lightsterilization as in previous experiments). Discs were placed into48-well plate (n=4), pre-washed in growth media for 1 h at 35° C./5%CO₂. Then the wash media was replaced with 0.5 mL MLO-A5 cell suspensioncontaining 2×10⁴ cells. After 24 hours and 48 hours in culture, cellviability was measured using the MTT assay and the number of live anddead cells was measured using the TBE assay. The results are summarizedin Table 6 and FIG. 1.

TABLE 5 Dual Chemical/Light Cured Silorane Resins Formulation Comparedto Light Cured Silorane Chem ID Bio ID SilMix AA PIH CPQ EDMAB SM17- DCA3 g 0.024 g 0.024 g 0.008 g 0 g DV-A SM17- DCB 3 g 0.048 g 0.048 g 0.016g 0 g DV-B SM17- DCC 3 g 0.096 g 0.096 g 0.032 g 0 g DV-C SM17 Light 3 g   0 g 0.094 g 0.031 g 0.005 g    PIH B initiated used as control AA =acetic acid; PIH = p-(octyloxyphenyl)phenyliodoniumhexafluoroantimonate; CPQ = camphorquinone; EDMAB = ethylp-dimethylaminobenzoate.

TABLE 6 Live and Dead Cell Numbers and Calculated Percent in the TrypanBlue Test. 24 h live cells 24 h dead cells 48 h live cells 48 h deadcells ID # cells ×10⁴ % # cells ×10⁴ % # cells ×10⁴ % # cells ×10⁴ %control 26 ± 1 89 3 ± 1 11 51 ± 9 89 6 ± 2 11 DCA  4 ± 3 43 5 ± 2 57  8± 2 65 3 ± 2 35 DCB  9 ± 3 68 4 ± 1 32  9 ± 3 66 5 ± 1 34 DCC 10 ± 3 753 ± 1 24 16 ± 4 81 4 ± 1 19 PIH (light) 15 ± 4 86   2 ± 0.5 14 24 ± 6 893 ± 1 10

The MTT results indicate that dual cured resins (DCB and DCC) producedadherent cell viability similar (p>0.05) to the photoinitiated siloraneresin PIH in 24 hours (FIG. 1, panel e) and 48 hours (FIG. 1, panel f)cultures. However, in the Trypan blue assay (Table 6), only the dualcured resin DCC produced live cell numbers (adherent and non adherent)similar (p>0.05) with the photoinitiated silorane resin PIH in 24 hours(FIG. 1, panel a) and 48 hours (FIG. 1, panel b) cultures.

From the MTT and Trypan blue results, the dual cured resin DCC is morebiocompatible than the others tested and was the most similar to thephotoinitiated silorane PIH. Among the dual cured resins, the resin DCCcontained more polymerization system (about 7%) than the other tworesins (DCB 3.6% and DCA 1.8%) which used decreasing amounts of aceticacid (Table 5). It is thought that with more initiator there is likelymore polymerization. Therefore, there would be less monomer and morereacted polymer resulting in less toxicity. However, since the deadcells (as number and percent) appear similar for all chemically cureresins, their decrease in cell numbers seem to be an effect of cellgrowth inhibition rather than cell death. Growth inhibition may haveoccurred because cells did not attach well to the polymer surfaces.

Example 4: Cytotoxicity of Neat Chemically Initiated Silorane Using LMC

In this example, the Lamoreaux's catalyst-cured resin (SilMix CC) wastested for in vitro biocompatibility and was found to be comparable tothe light cure silorane resin (SilMix LC). The formulations investigatedare shown in the following Table 7.

TABLE 7 Chemically cured silorane (SilMix CC) formula compared to lightcured silorane (SilMix LC) PHEPSI/CYGEP Polymer 1:1 (g) LMC (g) PIH (g)CPQ (g) EDMAB (g) SilMix LC is control and 3.00304 0.09405  0.031300.00468 light initiated (95.85%) (3.005%) (0.99%) (0.153%) SilMix CC4.00133 0.00274 0.000148 (99.89%) (0.07%)  (0.04%) LMC = Lamoreauxcatalyst; PIH = p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate;CPQ = camphorquinone; EDMAB = ethyl p-dimethylaminobenzoate

Polymer discs were prepared from both photoinitiated (LC) and chemicallyinitiated (CC) SilMix. The samples were sterilized on the day of assayusing two hour UV light exposure in a tissue culture laminar hood. Then,discs were placed into 48-well plate (n=3-4), pre-washed in growth mediafor one hour at 35° C./5% CO₂. The wash media was discarded and replacedwith 2×10⁴ MLO-A5 cells/0.5 mL. After 24 hours and 48 hours ofincubation, cell viability and proliferation was measured using thetrypan blue method. Another set of discs was used for extraction ofleachables by incubating the discs for 24 hours in culture media withserum. After 24 hours, the extracts were transferred to a monolayer ofMLO-A5 cells (seeded the day before). The cells were exposed to theextracts for 24 hours, after which the cell viability was measured usingthe MTT assay. Based on the trypan blue exclusion assay results, thenumber of live cells in the wells with the polymer SilMix LC and SilMixCC were less than (p<0.05) the control (plastic cell culture wells),while there was no significant difference in the number of dead cells.The percentage of live to dead cells with LC and CC SilMix was the sameas the controls (FIG. 2) showing that the reduction in cell number wasnot due to toxicity but was due to reduced proliferation. This is mostlikely due to reduced adherence to the polymer surface as bone cellshave been shown to require an attachment surface to proliferate. Thislack of cytotoxicity was confirmed in the MTT assay. The Formazanproduct in the presence of extracts from SilMix LC (OD=0.95±4) andSilMix CC (0.96±3) were similar to the controls (0.92±5). From theseresults, it is clear that the in vitro cytocompatibility of the chemicalcure SilMix is comparable to the photoinitiated SilMix in the 24 and 48hour cultures with bone like MLO-A5 cells.

Example 5: Stabilization of Fractured Excised Femur with DifferentlyCured SilMix Resin

In this example, the stabilization effects of a dual chemical/lightcured composition of the present invention was compared to that of aconventional light curing system. A halogen light (100 W) at a distanceof 18 inches was used to cure the system over a period of about 5minutes. The dual cure system comprised (A) co-monomer system SilMix(1:1 by weight of PHEPSI and CYGEP), 93 wt %; (B) weak Bronsteadacid—acetic acid, 3 wt %, (C) photoacid p-(octyloxyphenyl)phenyliodoniumhexafluoroantimonate, 3 wt %, and (D) photosensitizer, camphorqhinone 1wt %. For comparative purposes, a light cure system comprising 95.85 wt% SilMix, 3 wt % PIH, 1 wt % camphorquinone, and 0.15 wt % EDMAB wasused.

More specifically, in this example, functional studies have beendeveloped to determine the ability of filled SilMix to stabilize bone inanimal models. Pilot testing has begun on extracted and in vivo ratfemurs with a clean-cut fracture introduced with a circular saw. SilMixor control bone cement is applied around the bone creating a 1-mm wideby 1-2 mm thick band of composite material. The flexural strength of thestabilized bones is then determined using four-point bend testing. Theseinitial studies have revealed that the more elastic behavior of theSilMix is better suited to provide bone stability than the relativelybrittle bone cement (Simplex® P).

Six mice were sacrificed by authorized personnel. The femora were thenharvested from freshly sacrificed mice and stripped of soft tissues.Femora were fractured using a handheld circular saw. The fractured boneswere repositioned and stabilized with 50-70 μL of each SilMix resinsaround the fracture site (n=6/SilMix formulation). The resin was curedeither using a halogen lamp for 5 minutes (dual initiation SilMix) or adental curing lamp 3 times for 20 seconds (photoinitiated SilMix). Thestabilized bones were stored in a humidified atmosphere for 24 hours,and then tested biomechanically. The data (FIG. 3) show that there is nodifference between the photoinitiated and dual cured SilMix group.

Example 6: Characterization of Flexure Strength and Modulus of Neat BoneCement

As discussed above, the flexural strength and flexural modulus resultsfor the P1 system and P2 systems was investigated. The results areillustrated in panels a and b of FIG. 4. More specifically, panel a ofFIG. 4 illustrates the flexural strength while panel b of FIG. 4illustrates the flexural modulus of the P1 and P2 systems compared to aconventional PMMA system. P1 (aka BCM52) comprised 50 wt % SilMix, 0.1wt % PIH, 0.1 wt % Lamoreaux's catalyst, 35.8 wt % pre-polymerizedcrushed SilMix, and 14 wt % DY5 filler. P2 comprised 39.45 wt % SilMixwith a light initiation system (EDMAB 0.15 wt %; CQ 1 wt %; PIH; 3 wt %;SilMix 95.85 wt %), 0.56 wt % Lamoreaux's catalyst, and 59.99 wt % 3TOSUmodified DY5 filler. “P2 w/1TOSU-1” and “P2 w/1TOSU-2” were two separatebeams comprising 39.7 wt % SilMix with a light initiation system (EDMAB0.15 wt %; CQ 1 wt %; PIH, 3 wt %; SilMix 95.85 wt %), 0.3 wt %Lamoreaux's catalyst, and 60.01 wt % 1TOSU modified DY5 filler.

In separate experiments, the flexural strength and flexural modulus oftwo different P1-type of systems (Table 8) was investigated, the resultsof which are shown in FIG. 4 (panels c and d) and Table 9. It will beappreciated that these inventive systems are filled systems containingLamoreaux's catalyst.

TABLE 8 Exemplary P1 Systems % Pre- % Polymerized Sample Total (g)SilMix % PIH % LMC SilMix % DY5 BCM51 3.17682 42.18 0.10 0.10 45.8511.77 BCM52 2.67889 49.95 0.10 0.10 35.85 14.00

TABLE 9 Flexural Strength/Modulus of Exemplary P1 Systems Flexural TestStrength Modulus (MPa) (GPa) samples Mean StDev Mean StDev n MoldStorage BCM51 22.26 2.78 1.58 0.06 7 glass 24 hr/PBS BCM52 25.77 1.531.63 0.07 7 glass 24 hr/PBS

In this example, the stress-strain curve for a neat dual chemical/lightcure system having acetic acid was also determined as generally shown inpanel e of FIG. 4. The biomaterial composition comprised 93 wt % SilMix,3 wt % acetic acid, 3 wt % PIH, and 1 wt % camphorquinone. The dualchemical/light cured silorane required about 5 minute's exposure tohalogen light to polymerize. There was concern about the compatibilityof the mechanical testing molds that were developed for chemical curedmaterials. The compression cylinders are 1.2 cm long and 5 minutehalogen light exposure results in polymerization throughout thespecimen.

Seven flexure beams were produced of a reasonable quality (still somesmall flaws, mostly toward ends of beam where not directly affectingflexural testing). After 24 hours of dark storage at room temperature,these were loaded at a rate of 3.7 mm/min as previously with bonecement.

TABLE 10 Flexural Strength - Dual Cured Silorane (unfilled). beamstrength (MPa) strain modulus (MPa) 1 41.3 7.3% 1693.7 2 50.4 8.1%1908.1 3 74.1 9.8% 2222.9 4 57.5 8.3% 1724.0 5 42.5 8.2% 1417.6 6 55.66.7% 2627.7 7 40.7 6.9% 1626.8 Mean 51.7 7.9% 1888.7

These values (Table 10) were comparable to previously tested bone cementvalues. However, bone cement gave a yield strength instead of maximumstrength. The dual cured specimens show a brittle fracture (FIG. 4).

Example 7: Exotherms of Neat Chemically Initiated SilMix (SM)

In this example, the chemically cured composition comprised (A)co-monomer system SilMix (1:1 by weight of PHEPSI and CYGEP), 99.89 wt%; (B) photoacid p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate,0.04 wt %, and (C) organometallic catalyst, Lamoreaux's catalyst, 0.07wt %. As a control, the light initiated composition comprised (A)co-monomer system SilMix (1:1 by weight of PHEPSI and CYGEP), 95.85 wt%; and (B) light initiation system comprising 3.0 wt %p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate, about 1.0 wt %camphorquinone, and about 0.15 wt % ethyl 4-dimethylaminobenzoate.

Samples of approximately 120 mg were then placed on thermocouples.Thermocouples had been previously prepared by taping a delrin washer ona glass slide onto which the tip of the thermocouple was taped. The tipof the thermocouple was centered approximately in the delrin washer.Photoinitiated SM samples were also tested using a similar manner.However, after mixing samples were placed in the delrinwasher/thermocouple set-up and irradiated for two minutes with a dentalcuring lamp. Peak exotherm was collected from the plots as well as curetime, defined as the time from mixing to pass peak exotherm to reachhalf or max temperature (Table 11). Sample temperature plots are shownin FIG. 5 for both the photo and chemical initiated SilMix.

TABLE 11 Maximum exotherm measurements for photoinitiated and chemicallyinitiated silorane resins. Peak Exotherm (° C.) Cure time (s)Repetitions (n) Photoinitiated 127.2 (6.2) 51.4 (4.6) 9 Chemically  31.1(3.8) 159.7 (70.4) 6

It was also observed that the polymerization time and heat generated isdirectly proportion to the speed of mixing as well of material. Thinnersamples polymerize slower than larger samples. For example, 500 mg ofmaterial on glass slide polymerizes in 15 minutes (passes GNT); whereas,a 100 mg sample will take up to 45 minutes to polymerize. Also, thespeed of mixing generates more heat and aids in the polymerizationreaction. The LMC catalyst was mixed in by hand.

Example 8: Filled Chemically Initiated Silorane Exotherm

In this example, two formulations were tested (Table 12, FIG. 6). Bonecement mimics (BCM) 1/2 and 3/4 had the same composition but werederived from different batches of formulation. Bone cement mimic 5/6contained a lower amount of PIH and LMC. Due to the thinness of thesamples, it took approximately 30 minutes to complete cure to hardness(pass the one-lb GNT).

TABLE 12 Cure time of three silorane bone cement mimic formulations. % %Max Curing Time Sample SM % PIH LMC % CSM % DY5 (° C.) (sec) BCM 1 34.250.15 0.15 55.84 9.61 34.9 128 BCM 2 34.25 0.15 0.15 55.84 9.61 35.3 156BCM 3 34.25 0.15 0.15 55.84 9.61 29.5 247 BCM 4 34.25 0.15 0.15 55.849.61 32.7 243 BCM 5 34.27 0.10 0.11 55.91 9.61 27.0 88 BCM 6 34.27 0.100.11 55.91 9.61 27.0 96 SM—SilMix; PIH—phenyl iodonium salt;LMC—Lamoreaux's catalyst; CSM—crushed SM (polymerized); DY5—yttriumsilicate glass filler (unmodified)

Overall, exotherm temperatures of the chemically cured silorane bonecement mimics were well below 45° C. limit (FIG. 7). There was somevariability, likely due to difference in mixing techniques, time to addthe LMC, etc. Lower concentrations of LMC catalyst resulted in a lowerpeak exotherm and somewhat of a double peak in temperature. Theseresults were repeated, but only with two samples. Due to the narrowrange in temperatures (about 10° C.), the resolution of our currentthermocouple is inadequate (resulting in digitized plots). Need toidentify alternate temperature recording device (RTD, thermistor, etc.)with greater resolution.

Prophetic Example

It will be appreciated that biocompatibility is an important propertyfor any biomaterial compositions of the present invention. In additionto the MLO-A5 cell lines, the biocompatibility of the compositions ofthe present invention can be assessed using, for example, MSCs(mesenchymal stem cells from bone marrow), L929 (fibroblast like cells),and HUVEC (human umbilical vein endothelial cells). Further, todetermine the potential of the silorane compositions to inducemineralization as another measure of its biocompatibility with bone,differentiation assays, such as alkaline-phosphatase, and mineralizationassays, such as alizarin red and von Kossa staining, may be performed onthe MLO-A5 cell line. These tests will determine the effect of thepolymer on the ability of cells to proliferate, differentiate, and formmineralized matrix.

Small Animal (Rat) Model: Pull-Out Strength Ex Vivo:

These studies will be conducted according to published methods whichhave been used as an in vivo model for implants. Male Sprague-Dawleyrats (approximately 6 months old) will be sacrificed and kept in −80° C.freezer. The femora will be excised. A 2 mm hole will be drilled intothe intercondylar notch with a Dremel drill bit to penetrate thesubchondral cortical bone and gain access to the femoral intramedullarycanal. The marrow cavity will be disrupted by inserting a threaded handdrill proximally through the entire length of the diaphysis toapproximately the level of the lesser trochanter. A guide implant willbe placed into the ablated cavity to ensure that the canal will be anappropriate size to accommodate the definitive implant. The cavity willthen be flushed with 10 mL of sterile saline for removal of loose marrowcontents. Following irrigation, bone cement (chemically cured siloraneand fillers (bone cement mimic) or commercial bone cement) will beintroduced into the intramedullary canal with a root canal filler andthen a titanium implant, 22 mm long and 1.5 mm diameter, will beimplanted in a retrograde manner. The femora implanted with titaniumrods fixed with bone cement mimic or commercial bone cement will be kept24 hours and tested biomechanically. The 2-4 mm of distal rod (implant)will be exposed; proximal half of femur will be embedded in dentalacrylic in a holder. The holder is a lower part of a 15 mL centrifugetube which is cut at mark-line 3 mL and can be filled 3 g of dentalacrylic and is attached an eye hook at bottom. The exposed implant willbe gripped with a drill chuck and S hooks will be placed at lower end ofthe specimen to keep coaxial alignment of the implant with the directionof force. The pullout test will be conducted at a displacement rate of0.25 mm/min to failure with the force (N). The values will be calculatedby dividing the force at the point of failure by the surface area of theimplant in the femur. This result will determine if the silorane basedbone cement provides adequate mechanical support.

Osteointegration of the Silorane Bone Cement In Vivo:

After ex vivo testing, the osseointegration with the silorane bonecement or PMMA bone cement will be assessed. The general biologicalresponse, including inflammation and bone mineralization, must also becharacterized for the silorane bone cements. The samples will be splitinto two parts: pull-out strength and histological analysis.

Implant Placement:

Male Sprague-Dawley rats (approximately 6 months old) will be placedunder general anesthesia via isofluorane inhalation (3-4% forinduction), ketamine/dex-medetomidine (75/0.5 mg/kg body weight; IP) formaintenance. The animal will be weighed and the both legs will be shavedwith a standard clipper and disinfected with povidone/iodine solution.Animals will be placed on a warming pad during surgery as provided inthe animal facility (recirculating water heating pad). All procedureswill be performed under aseptic conditions. A 1 cm lateral parapatellarincision will be made to expose the knee joint. The patella will beretracted medially with the knee extended. The knee will be slowlyflexed to expose the intercondylar notch. A 2 mm hole will be drilledinto the intercondylar notch with a Dremel drill bit to penetrate thesubchondral cortical bone and gain access to the femoral intramedullarycanal. The marrow cavity will be disrupted by inserting a threaded handdrill proximally through the entire length of the diaphysis toapproximately the level of the lesser trochanter. A guide implant willbe placed into the ablated cavity to ensure that the canal will be anappropriate size to accommodate the definitive implant. The cavity willthen be flushed with 10 mL of sterile saline for removal of loose marrowcontents. Following irrigation, bone cement (chemically cured siloraneand fillers or commercial bone cement) will be introduced into theintramedullary canal, and then a titanium implant, 22 mm long and 1.5 mmdiameter, will be implanted in a retrograde manner. The capsule and skinwill be sutured with 4-0 nylon. Buprenex, 0.01-0.05 mg/kg andAtipamezole, 0.1-1 mg/kg will be administered intraperitoneally to therat immediately post operation. The animal will be allowed to fullyrecover in a separate cage on the warming pad and will be allowedactivity ad libitum.

Post-Op Analysis:

The inflammatory response of incision and movement of operated limb willbe monitored every day. Microcomputed tomography (MicroCT) and X-raywill be taken at weeks 1, 4, and 8 weeks post surgery. Animals will beeuthanized by CO₂ asphyxiation at 1 (to examine for any inflammatoryreaction) and 8 weeks (to examine for osseointegration) post surgery.The femurs for mechanical testing will be harvested, denuded of softtissue, and frozen at −20° C. The procedure of mechanical test could beseen above. The femurs for histology will be placed in 10% neutralbuffered formalin.

Tissue Preparation, Histology, and Histomorphometry:

After placement and sacrifice, bones will be fixed in neutral bufferedformalin, decalcified and embedded for frozen sections by standardtechniques. Serial sections will be cut and stained with Hematoxylin andEosin (H&E) or Goldner's trichrome using standard techniques. Stainingfor both TRAP and alkaline phosphatase can be performed. Undecalcifiedmethacrylate embedded sections will also be stained by the von Kossaprocedure as described previously for determination of the mineralizedbone volume by histomorphometry.

Histomorphometric Analysis:

Histomorphometric analysis will be performed on long bones using a NikonE800 microscope with live video image capabilities that is interfacedwith the Osteomeasure bone histomorphometry software. The parameters tobe measured from H&E and/or Goldner's trichrome stained sections includetrabecular and cortical bone volume, osteoid seam thickness, andosteoblast numbers per mm bone surface. TRAP stained sections will beused for determination of the number of osteoclasts per mm bone surface.Von Kossa stained sections will be used to measure the volume ofmineralized bone which will be expressed as a percentage of the totalbone volume (i.e., including osteoid). Three non-consecutive sections(100 μm apart) from each specimen will be used for the histomorphometricanalyses described above and these measurements will be performed by anindividual who is without knowledge of the sample identities. Valueswill be expressed as the mean±standard error. Examination for weardebris particles in the surrounding tissue will be performed.

All publications, patents, patent applications, databases, and otherreferences cited in this application are herein incorporated byreference in their entirety as if each individual publication, patent,patent application, database, or other reference were specifically andindividually indicated to be incorporated by reference.

-   Aoki, U.S. Pat. No. 6,255,428 for Preparation of Epoxy Group-Bearing    Organopolysiloxane or Organosilane (2001)-   Beyer et al., Mesenchymal stem cells: isolation, in vitro expansion    and characterization, Handbook Exp Pharmacol 174 249-282 (2006)-   Bonewald et al., Staining alone is not sufficient to confirm that    mineralizatiosn in vitro represents bone formation, Calcified Tissue    International 72(5) 537-547 (2003)-   Bonewald, Mechanosensation and Transduction in Osteocytes, BoneKey    3(10) 7-15 (2006)-   Chappelow et al., Photopolymerization of a Novel    Tetraoxaspiroundecane and Silicon-Containing Oxiranes, J Appl Polym    Sci 103(1) 336-344 (2006)-   Chappelow et al., Photopolymerization of Stress-Reducing    Tetraoxaspiro[5.5]undecanes in Silorane-Based Matrix Resins, J Dent    Res 85 (SI-A) Abstract No. 823 (2006)-   Chappelow et al., U.S. Provisional Patent No. 60/721,806 (Sep. 29,    2005)-   Cornell, Experiments with mixtures: designs, models, and the    analysis of mixture data, New York Wiley xix 649 3rd ed. (2002)-   Crivello et al., The synthesis and cationic polymerization of    multifunctional silicon-containing epoxy monomers and oligomers, J    Polym Sci Part A Polym Chem 32 683-697 (1994)-   Dunne et al., Curing characteristics of acrylic bone cement, J Mater    Sci Mater Med 13(1) 17-22 (2002)-   Edgell et al., Permanent cell line expressing human factor    VIII-related antigen established by hybridization, Proc Natl Acad    Sci USA 80(12) 3734-3737 (1983)-   Eick et al., In vitro biocompatibility of oxirane/polyol dental    composites with promising physical properties, Dent Mater 18(5)    413-421 (2002)-   Eick et al., Physical Properties of Silorane-Based Matrix Resins    Containing Stress-Reducing Monomers, J Dent Res 85 (SI-A) Abstract    No. 897 (2006)-   Eick et al., Stability of silorane dental monomers in aqueous    systems, J Dent. 34(6) 405-410 (2006)-   Eick et al., Properties of silorane-based dental resins and    composites containing a stress-reducing monomer, Dent Mater 23(8)    1011-1017 (2007)-   Eick et al., Mineralization Potential of Silorane and BISGMA/TEGDEMA    Resins, 85th Intl Assoc Dent Res Ann Mtg, Abstract No. 1393 (2007)-   Eick et al., Expandable monomer silicon analogs and siloranes: II.    physical properties testing, J Dent Res 84 Abstract No. 1467 (2005)-   Feng, Dentin matrix protein 1, a target molecule for Cbfa1 in bone,    is a unique bone marker gene, Journal of Bone and Mineral Research    17(10) 1822-1831 (2002)-   Feng et al., Loss of DMP1 Causes Rickets and Osteomalacia and    Identifies a Role for Osteocytes in Mineral Metabolism, Nature    Genetic 38 1310-1315 (2006)-   Giese et al., Determining Polymerization Volume Change of Oxiranes    and Methacrylates Using Mercury Dilatometry, 229th ACS National    Meeting: Abstracts of Papers: ANYL-265 (2005)-   Gomoll et al., Nanoparticulate fillers improve the mechanical    strength of bone cement, Acta Orthop 79(3) 421-427 (2008)-   Guggenberger et al., Exploring beyond methacrylates, Am J Dent 13    82D-84D (2000)-   Guida et al., Biological response of human bone marrow mesenchymal    stem cells to fluoride-modified titanium surfaces, Clin Oral    Implants Res 21(11) 1234-1241 (2010)-   Holder et al., Toward a Cohesive Theory of Polymerization Volume    Change, 1: General Requirements and Oxiranes, Macromol Th Simulat 14    117-124 (2005)-   Holder et al., Rational Design of Dental Materials Using    Computational Chemistry, Dent Mater 21(1) 47-55 (2005)-   Holder et al., An Application of QM-QSAR to Predict and Rationalize    the Refractive Index of a Wide Variety of Simple    Organic/Organosilican Molecules, QSAR Combin Sci 25(4) 342-349    (2006)-   Ilie et al., Silorane-based dental composite: behavior and    abilities, Dent Mater J 25(3) 445-454 (2006)-   Ilie et al., Macro-, micro- and nano-mechanical investigations on    silorane and methacrylate-based composites, Dent Mater 25(6) 810-819    (2009)-   ISO, Implants for surgery—Acrylic resin cements, Geneva, Switzerland    (2002)-   Kato et al., Establishment of an osteoid preosteocyte-like cell    MLO-A5 that spontaneously mineralizes in culture, J Bone Miner Res    16(9) 1622-1633 (2001)-   Kilway et al., Molecular Assembly of 1,3,5-Tris(cyanomethyl) and    1,4-Bis(cyanomethyl) Arenes with Silver Triflate, Pure Appl Chem    78(4) 855-871 (2006)-   Kostoryz et al., Effects of dental resins on TNF-alpha-induced    ICAM-1 expression in endothelial cells, J Dent Res 80(9) 1789-1792    (2001)-   Kostoryz et al., Assessment of Relative Skin Sensitization Potency    of Dental Monomers, J Biomed Mater Res 79(3) 684-688 (2006)-   Kostoryz et al., Cytotoxicity evaluation of silorane polymers in    odontoblast like cells, J. Dent. Res 85(A) Abstract #1654 (2006)-   Kostoryz et al., Assessment of cytotoxicity and DNA damage exhibited    by siloranes and oxiranes in cultured mammalian cells, Mutat Res    634(1-2) 156-162 (2007)-   Kuehn et al., Acrylic bone cements: mechanical and physical    properties, Orthop Clin North Am 36(1) 29-39 (2005)-   Lamoreaux, U.S. Pat. No. 3,220,972 for Organosilicon Process Using a    Chloroplatinic Acid Reaction Product as the Catalyst (1965)-   Lane et al., Glucocorticoid-Treated Mice Have Localized Changes in    Trabecular Bone aterial Properties and Osteocyte Lacunar Size That    Are Not Observed in Placebo-Treated or Estrogen-Deficient Mice, J    Bone Miner Res 21(3) 466-476 (2006)-   Lewis, Alternative acrylic bone cement formulations for cemented    arthroplasties: present status, key issues, and future prospects,    Journal of Biomedical Materials Research Part B, Applied    Biomaterials 84(2) 301-319 (2008)-   Lien et al., Physical properties of a new silorane-based restorative    system, Dent Mater 26(4) 337-344 (2010)-   Miller et al., A Theoretical Study of an Expanding Monomer and an    Oxirane Part 2: Oxirane and Copolymer Reactions, J Mol Struct    THEOCHEM 756(1-3) 195-203 (2005)-   Miller et al., Matrix-Assisted Laser Desorption/Ionization    Time-of-Flight Analysis of the Copolymerization Reaction of an    Expanding Monomer with a Diepoxide, J Polym Sci [A1] 43(23)    5962-5970 (2005)-   Mosna et al., Human Bone-Marrow And Adipose Tissue Mesenchymal Stem    Cells: A User's Guide, Stem Cells Dev.-   Nalvarte-Kostoryz et al., Biocompatibility of the silorane resin to    develop biomaterials for temporary bone stabilization, J. Biomed.    Mater. Res. Part B Applied Biomaterials (in press).-   Nicolella et al., Osteocyte Lacunae Tissue Strain in Cortical Bone,    J Biomech 39(9) 1735-1743 (2006)-   Piepel et al., Mixture experiment approaches: examples, discussion,    and recommendations, J Qual Tech 26(3) 177-195 (1994)-   Puska et al., Flexural properties of crosslinked and    oligomer-modified glass-fibre reinforced acrylic bone cement, J    Mater Sci Mater Med 15(9) 1037-1043 (2004)-   Radev et al., Potential for thermal damage to articular cartilage by    PMMA reconstruction of a bone cavity following tumor excision: a    finite element study, J Biomech 42(8) 1120-1126 (2009)-   Ries et al., In vivo behavior of acrylic bone cement in total hip    arthroplasty, Biomaterials 27(2) 256-261 (2006)-   Ritter et al., Systemic effects of polymethylmethacrylate: increased    serum levels of gamma-glutamyltranspeptidase following arthroplasty,    Acta Orthop Scand 55(4) 411-413 (1984)-   Saha et al., Mechanical properties of bone cement: a review, J    Biomed Mater Res 18(4) 435-462 (1984)-   Sanford et al., The growth in vitro of single isolated tissue cells,    J Natl Cancer Inst 9(3) 229-246 (1948)-   Sena et al., Effect of recombinant human transforming growth    factor-beta2 dose on bone formation in rat femur titanium implant    model, J Biomed Mater Res A. 92(3) 1210-1217 (2010)-   Sengun et al., Cytotoxicity of Silorane-Based Composite in a Dentin    Barrier Test, J Dent Res 84(A) Abstract #0122 (2005)-   Spencer et al., Micro-Raman Spectroscopy: Principles and    Applications in Dental Research, Photonics in Dentistry, Editor    Kishen, A (in press).-   Wang et al., Effect of Co-Initiator and Water on the Photoreactivity    and Photopolymerization of HEMA/Camphoquinone-Based Reactant    Mixtures, J Biomed Mater Res 78 721-728 (2006)-   Wang et al., Comparison of Interfacial Characteristics of Adhesive    Bonding to Superficial Versus Deep Dentin Using SEM and Staining    Techniques, J Dent 34 26-34 (2006)-   Wang et al., Micro-Raman Imaging Analysis of Monomer/Mineral    Distribution in Intertubular Region of Adhesive/Dentin Interfaces, J    Biomed Opt 11:024005/1-024005/7 (2006)-   Weinmann et al., Siloranes in dental composites, Dent Mater 21(1)    68-74 (2005)-   Ye et al., Relationship of Photopolymerization Processes, Structure    and Properties in Dentin Adhesives, J Biomed Mater Res A 80 342-350    (2006)-   Zhang et al., E11/Gp38 Selective Expression in Osteocytes:    Regulation by Mechanical Strain and Role in Dendrite Elongation, Mol    Cell Biol 26(12) 4539-4552 (2006)

From the foregoing it will be seen that this invention is one welladapted to attain all ends and objectives herein-above set forth,together with the other advantages which are obvious and which areinherent to the invention. Since many possible embodiments may be madeof the invention without departing from the scope thereof, it is to beunderstood that all matters herein set forth or shown in theaccompanying figures are to be interpreted as illustrative, and not in alimiting sense. While specific embodiments have been shown anddiscussed, various modifications may of course be made, and theinvention is not limited to the specific forms or arrangement of partsand steps described herein, except insofar as such limitations areincluded in the following claims. Further, it will be understood thatcertain features and subcombinations are of utility and may be employedwithout reference to other features and subcombinations. This iscontemplated by and is within the scope of the claims.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. A biomaterial composition comprising: a polymerizablesilorane monomer, and a curing system selected from the group consistingof a chemical curing system and a dual chemical/light curing systemwherein said silorane monomer comprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof, and further comprising a filler wherein saidfiller comprises a pre-polymerized polymer derived from saidpolymerizable silorane monomer.
 2. The biomaterial composition of claim1 wherein said acid is a Lewis acid.
 3. The biomaterial composition ofclaim 1 wherein said acid is selected from the group consisting ofacetic acid, phosphoric acid, sulfuric acid, hydrobromic acid,hydroiodic acid, trichloroacetic acid, trifluoroacetic acid,p-toluenesulfonic acid, boron trifluoride, aluminium chloride, tin (IV)chloride, titanium chloride, pentafluoroproprionic acid, triflic acid,hexafluorophosphoric acid, and mixtures thereof.
 4. The biomaterialcomposition of claim 1 wherein said curing system further comprises aphotoacid.
 5. The biomaterial composition of claim 1 wherein saidphotoacid is a phenyliodonium compound.
 6. The biomaterial compositionof claim 5 wherein said photoacid is selected from the group consistingof (4-n-octyloxyphenyl)phenyliodonium hexafluoroantimonate,[4-(2-hydroxy-tetradecyloxyphenyl)]phenyliodonium hexafluoroantimonate,[4-1-methylethyl)-phenyl](4-methylphenyl)iodoniumtetrakis(pentafluorophenyl)borate(1-), and combinations thereof.
 7. Thebiomaterial composition of claim 1 wherein said curing system is a dualchemical/light curing system further comprising a photosensitizer. 8.The biomaterial composition of claim 7 wherein said photosensitizer is adiketone.
 9. The biomaterial composition of claim 1 wherein said curingsystem is a dual chemical/light curing system further comprising anelectron donor compound in which said electron donor comprises asubstituted amine.
 10. The biomaterial composition of claim 1 whereinsaid curing system is a dual chemical/light curing system furthercomprising a light initiation system having a photoacid, aphotosensitizer, and an electron donor.
 11. The biomaterial compositionof claim 1 further comprising one or more tetraoxaspiro[5.5]undecanes.12. The biomaterial composition of claim 1 comprising 30 to 60 wt %silorane monomers; 1 to 50 wt % of the pre-polymerized polymer derivedfrom the silorane monomers; and 0.05 to 5 wt % of the curing system. 13.The biomaterial composition of claim 12, wherein the compositioncomprises additional fillers in addition to said pre-polymerizedpolymers.
 14. The biomaterial composition of claim 12, wherein thecomposition comprises 0 to 25% additional fillers in addition to saidpre-polymerized polymers.
 15. The biomaterial composition of claim 1,wherein said filler further comprises a filler selected from the groupconsisting of glass fillers, ceramic fillers and combinations thereof.16. The biomaterial composition of claim 15, wherein said glass fillersand said ceramic fillers comprise surface modified fillers.
 17. Thebiomaterial composition of claim 15, comprising 20 to 60 wt % siloranemonomers; 1 to 80 wt % of the glass fillers, ceramic fillers orcombinations thereof; and 0.05 to 5 wt % of the curing system.
 18. Thecomposition of claim 1, wherein the ratio of CYGEP to PHEPSI is 1:1(w/w).
 19. The biomaterial composition of claim 1 further comprising oneor more tetraoxaspiro[5.5]undecanes.
 20. The biomaterial composition ofclaim 19, wherein said tetraoxaspiro[5.5]undecane is selected from thegroup consisting of a 2,4,8,10-tetraoxaspiro[5.5]undecane or a1,5,7,11-tetraoxaspiro[5.5]undecane.
 21. The biomaterial composition ofclaim 19, wherein said tetraoxaspiro[5.5]undecane is selected fromFormulas A1 and A2

wherein R₁ and R₃ are independently is alkyl, aryl, aralkyl, orhydrogen; and wherein R₂ and R₄ are independently alkenoxy,alkenoxyalkyl, or silicon-containing moiety selected from alkylsilyl,arylsilyl, arylalkylsilyl, alloxysilyl, aryloxysilyl, arylalkoxysilyl,alkylsiloxy, arylsiloxy, arylalkylsiloxy, alkoxysiloxy, aryloxysiloxy,arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl, arylalkysilylalkyl,alkoxysilylalkyl, aryloxysilylalkyl, arylalkoxysilylalkyl, alkylsiloxyalkyl, arylsiloxyalkyl, arylalkylsiloxyalkyl, alkoxysiloxyalkyl,aryloxysiloxyalkyl, arylalkoxysiloxyalkyl, alkylsilylalkoxy,arylsilylalkoxy, arylalkylsilylalkoxy, alkoxysilylalkoxy,aryloxysilylalkoxy arylalkyloxysilylalkoxy, alkylsiloxyalkoxy,arylsiloxyalkoxy, arylalkylsiloxyalkoxy, alkoxysiloxyalkoxy,aryloxysiloxyalkoxy, and arylalkoxysiloxyalkoxy.
 22. The biomaterialcomposition of claim 19, wherein said tetraoxaspiro[5,5]undecane isselected from the group consisting of3,9-diethyl-3,9-bis(allyloxymethyl)-1,5,7,11-tetraoxaspiro[5.5]undecane(DEBAOM-1,5,7,11-TOSU);3,9-bis(3-trimethylsilylpropyl)-1,5,7,11-tetraoxaspiro[5.5]undecane(BTMSP-1,5,7,11-TOSU);3,9-bis(allyloxymethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(BAOM-2,4,8,10-TOSU);3,9-bis(2-trimethylsilylethyl)-2,3,8,10-tetraoxaspiro[5.5]undecane(BTMSE-2,4,8,10-TOSU); 5,5-diethyl-19-oxadispiro[1,3-dioxane-2,2′-1,3-dioxane-5′,4″-bicyclo[4.1.0]heptane](DECHE-1,5,7,11-TOSU);3,9-diethyl-3,9-bis(3-trimethylsilylpropyloxymethyl)-1,5,7,11-tetraoxaspiro[5.5]-undecane(DEBTMSPOM-1,5,7,11-TOSU);(9-allyloxymethyl-9-ethyl-1,5,7,11-tetraoxaspero[5.5]undec-3-ylmethyl)-dimethylphenyl-silane(AOME-TOSU-MDMPS); andmethyl[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-phenyl[3-(3,9,9-triethyl-1,5,7,11-tetraoxaspiro[5.5]undec-3-ylmethoxy)propyl]silane(MOB-REP-TETOSU-MOPS).
 23. The biomaterial composition of claim 1wherein said composition after polymerization exhibits a peak exothermbelow 35° C.
 24. The biomaterial composition of claim 1 wherein saidcomposition after polymerization exhibits a flexural strength of 20 to65 MPa.
 25. The biomaterial composition of claim 1 wherein saidcomposition after polymerization exhibits a flexural strength of greaterthan 65 MPa.
 26. The biomaterial composition of claim 1 wherein saidcomposition after polymerization exhibits a flexural modulus 1.5 to 4GPa.
 27. The biomaterial composition of claim 1, wherein the compositioncomprises 1-80% filler.
 28. The biomaterial composition of claim 27,wherein the composition comprises 1-75% filler.
 29. A biomaterialcomposition comprising: a polymerizable silorane monomer, and a curingsystem selected from the group consisting of a chemical curing systemand a dual chemical/light curing system wherein said silorane monomercomprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof; and wherein said curing system is a dualchemical/light curing system further comprising acetic acid,p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate, andcamphorquinone.
 30. The biomaterial composition of claim 29 furthercomprising a filler.
 31. A biomaterial composition comprising: apolymerizable silorane monomer, and a curing system selected from thegroup consisting of a chemical curing system and a dual chemical/lightcuring system wherein said silorane monomer comprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof; wherein said curing system is a dualchemical/light curing system further comprising a light initiationsystem having a photoacid, a photosensitizer, and an electron donor;said acid is a Lewis acid, and said Lewis acid comprises acetic acid;said photoacid is a phenyliodonium compound, and said photoacidcomprises p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate; saidphotosensitizer is a diketone, and said photosensitizer comprisescamphorquinone; and and said electron donor is a substituted amine, andsaid electron donor comprises ethyl p-dimethylaminobenzoate.
 32. Thebiomaterial composition of claim 31 further comprising a filler.
 33. Thebiomaterial composition of claim 32, comprising 1 to 80 wt % of saidfiller.
 34. A biomaterial composition comprising: a polymerizablesilorane monomer, and a curing system selected from the group consistingof a chemical curing system and a dual chemical/light curing systemwherein said silorane monomer comprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof; and further comprising a filler, wherein saidfiller comprises a filler selected from the group consisting of glassfillers, ceramic fillers and combinations thereof, and wherein saidglass fillers and said ceramic fillers comprise surface modifiedfillers, and wherein said surface modified filler comprises a surfacemodifier selected from 2-(3,4 ethyl cyclohexyl epoxy) trialkoxy silane(ECHE),[(9,9-diethyl-1,5,7,11-tetraoxa-spiro[5,5]undec-3-yl)-methyl]-trimethoxysilane(1-TOSU), or [3-(9,9-diethyl-1,5,7,11-tetraoxa-spiro[5,5]undec-3-yl)-propyl]-trimethoxysilane(3-TOSU).
 35. A biomaterial composition comprising: a polymerizablesilorane monomer, and a curing system selected from the group consistingof a chemical curing system and a dual chemical/light curing systemwherein said silorane monomer comprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof; and further comprising an antimicrobial,antibiotic, or growth factor that is stable at 25 to 30° C.
 36. Abiomaterial composition comprising: a polymerizable silorane monomer,and a curing system selected from the group consisting of a chemicalcuring system and a dual chemical/light curing system wherein saidsilorane monomer comprises a mixture of2,4,6,8-tetramethyl-2,4,6,8-tetrakis-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]-1,3,5,7-tetraoxa-2,4,6,8-tetrasilacyclooxtane(CYGEP) and methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane(PHEPSI), and wherein said curing system comprises an acid selected fromthe group consisting of a Bronsted acid, Lewis acid, and a superacid,and mixtures thereof, and further comprising a growth factor selectedfrom the group consisting of TGFβ1, TGFβ2, TGFβ3, BMP-2, BMP-3, BMP-4,BMP-5, BMP-6, BMP-7, BMP-8, BMP-9, CDMP-1, CDMP-2, or CDMP-3.